 I think I told you in the first lecture itself an introduction to distillation that normally reactive distillation is treated as a special case of distillation like you have an enhanced distillation in which you have a azeotropic distillation, extractive distillation and then they talk about reactive distillation. But that is not true in a sense because reactive distillation is not just a distillation technique or it is not just an enhanced distillation technique because it is not just a distillation column or a separator but it is a reactor as well. So it is not only used for separations but it is used for reactions as well and of course as the name says it is the combination of reaction and distillation in a single unit. That means in a column on every stage or a particular zone the reaction is taking place. Now I put a catalyst or sometimes it is uncatalyzed reaction that reaction is taking place. In that case how the things change? Can I have a design methodology for reactive distillation? Let us discuss all these issues but before that I thought let us understand the commercial applications of reactive distillation like. So I am going to take you to a different world now not really the separation techniques and vapor liquid equilibrium but I am going to talk about different processes, commercially important processes where reactive distillation can be used. So we are going to talk about chemicals, chemistry, reactions and all that. So we are adding another dimension to our process that is reaction, so your reaction taking place and reaction can be as complicated as possible. You can have the kinetics depending on what kind of catalyst you use. It can be solid catalyst, it can be liquid catalyst and depending on that you have complex kinetics and will affect your reaction to a great extent or distillation to a great extent. It is also called as a multifunctional reactor, reactive distillation is also called as a multifunctional reactor. That means my purpose is to do reaction and then the distillation will help reaction so that some enhanced performance is achieved. So it is not just a distillation column, you can call it as a reactor in which distillation is employed or it can be a distillation column in which reaction is employed depending on the application that we are looking at. So it should be taken, reactive distillation term should be taken in a very broader sense as far as its applications are concerned. This is something that we have seen in the very first lecture, I will just repeat. You have simple reaction A plus B giving C plus D, it is a reversible reaction, equilibrium controlled reaction or rather it is affected or influenced by equilibrium. So if you do this reaction in simple reactor, law of mass action says that you get equilibrium conversion. So if you do it in the CSTR, how much your residence time you put in or rather you provide, you are going to get equilibrium conversion. But then if you remove one of the products simultaneously during the course of the reaction, then reaction can be shifted in forward direction, leach at least principle, very simple. So in this case what I am doing is C, let C is the more volatile or most volatile component in the system. So I do the reaction in boiling condition so that I have vapor going out and liquid going out. So two streams coming out of this reactor. Now this will be enriched in C, but along with C you have A and B and A, B and D and here you have ABD. But then this reactor will perform better than normal reactor where you have only one liquid coming out because you simultaneously remove C and because remove of C, the concentration in C in the reactor will be reduced and if you look at law of mass action, this will be reduced so that the reaction will shift in forward direction. But then you have problems because you are removing A, B, D along with C, there are losses of these. Can I avoid that? I will put a column and selectively remove C, efficiently I will remove C with the reflux and all and if the system is ideal, now you know, if the system is ideal I can remove pure C from the top. If the system is ideal, if there is a exertor form then you have limitations. So you are recycling ABD back to the column and same is true here if D is the least volatile component. See I am putting some conditions, if D is the least volatile component then I have a stripper there and I am selectively or efficiently removing D through a normal distillation technique. Now you consider the entire assembly, you have reactor followed by two distillation column. Can I just scrub this reactor along or other, combine this reactor along with the separation units and I have a normal reactor distillation column, conventional reactant distillation column. Where the red part shows that, the reaction is taking place. And you have the blue part, where there is only distillation taking place. So this column is equivalent to this section of the column, this column is equivalent to the section of the reactor distillation column and this part where reaction is taking place is equivalent to this section of the column. So, you have this is called in hybrid reactive distillation column and if I have A B that is reactants going in to the column I am not shown that here, then you have C and D coming out from top and bottom right. So, this is possible right this is possible of course there are many questions can I do the reaction as efficiently as what I was doing here ok this is stirring here we do not have stirring. But then of course like the reaction is relatively fast it depends on the chemistry and the catalyst that we use. You can avoid or you can get you can use efficient column internals can have good column hydrodynamics. So, that the reaction is not affected by a mass transfer limitations and all. But as far as the flow pattern is concerned it will be a plug flow type behavior compared to what you have here you have a CSTR there ok, but in fact sometimes plug flow is better right. So, you have a typical reactive distillation column where the feed is going in A and B and you are getting C and D products out ok. Now, you can imagine like this is really going to be an achievement if you can do this because normally a chemical plant would have what reactor you have insufficient conversion you have unreacted reactants then you have products you have to take this stream out then you have chain of distillation columns right and then your recycles many things right. If you can I can achieve all this in a single piece of equipment then nothing like that it is a good tool for process integration right. You are bringing all the components of the process together you are condensing the entire process in a single piece of equipment ok. You are bringing cost effectiveness and compactness of a chemical plant ok. So, that is reactive distillation and it is not just though I have considered a hypothetical example here it is not it is not as I said like in the first lecture itself it is not a not just an idea or concept it is commercially applied like for example, the reaction of acetic acid with methanol giving methyl acetate and water ok. So, you have both acetic acid and methanol going to the column from the top you get methyl acetate from the bottom you get water ok. I am going to see that I am going to tell you more details about that reaction later, but then this is practice ok this is commercial ok. The entire plant is condensing in a single unit ok. So, that is the potential of reactive distillation. So, it is not just the separator it is a process it is a process. So, it is combination of reaction and distillation. So, it is bringing all the components of the process together of course, it has its own limitation it is not that we can apply reactive distillation for all the reactions like the major limitation like where I was explaining this I am making many assumptions I was saying that C is most volatile in this volatile. So, all this may not be true in every case right. So, those conditions should match now there will be certain temperature at that temperature reaction should take place. Now distillation distillation there is a temperature is decided by the boiling point bubble point right and that temperature should be same as the temperature required for the reaction ok. If that these two temperatures do not match then you have constraints ok. Of course, there is a ways to play with pressure ok and play with pressure and increase the temperature or reduce the temperature and get the reaction going ok, but then we have to work out economics and all right. So, this is an example where I have started with reaction ok and I showed how the distillation would help the reaction get going in forward direction, but there are applications where you are struggling to separate a mixture like the example that I gave you A plus B difficult to separate means you may have formation of azeotrope or the mixture or other components are close boiling ok. Normally a technique non reactive techniques are azeotropic distillation or extractive distillation you add third component ok. In extractive it will change your VLE favorably in azeotrope it will form an azeotrope atrogenous azeotrope you can use reactive distillation also and add this C, C will react right, C will react with other A or B ok. It will form a product and this product ok it is having it may be having a relative volatility which is higher or lower than the other component right and you can separate this product right you can separate this product and convert it back later on or can sell if it has a market ok. So, I can achieve the separation by reactive distillation ok that is why it is considered as a special case of distillation ok. There is a purpose to separate a mixture ok, but the example that I gave you here the first objective is to get a reaction going right. So, this is difference right. So, it is quite possible to use reactive distillation for enhancing the reaction performance and at the same time it is quite possible to use reactive distillation for doing separation for a difficult to separate system where you have formation of azeotrope or close boiling mixture right and the applications that we are going to see they are mixed rather in sense rather sometimes distillation is helping reaction sometimes reaction is helping distillation and so on right. So, it falls in the category of multifunctional reactors ok it is a very popular concept these days ok try and combine reaction with something else. Now, this something else can be either separation heat transfer momentum transfer and all that is why reactive distillation comes in the category of multifunctional reactors where I am combining reaction with distillation ok. I see the purpose is to enhance the performance ok see the reaction is synergistically enhanced by means of integrating with one or more operations in this case is just one operation right. So, I am combining distillation in reaction so as to enhance the overall performance of the process. Now, enhance the performance means what it can be increasing conversion, it can be increasing selectivity, it can be reduction in energy cost, it can be reduction in capital cost you can imagine ok entire plant in contains in one unit. Now, much saving would be there in your equipment cost right recycle cost ok. So, it is not a new concept it is not a new concept way back in 1869 like solvage process like to produce soda ash like. So, they use this concept doing reaction together with distillation ok. The ammonia recovery in that particular process is done through reactive stripping ok. So, the concept is not new why I am I have put this slide here is to tell you that even in 1869 it was practiced, but not under the name reactive distillation ok. The concept is not new reaction is not new for chemical engineers distillation is not new for chemical engineers. So, combining them is not a problem so it was practiced, but the analysis today available is quite exhausted many people are working. So, as to apply this particular concept effectively and efficiently to many other processes right and of course it was applied, but not much analysis was available there not much theoretical understanding was available there. So, later on of course, people have started working on it and nowadays it has become very popular mainly because now we have the tools like simulation modelling and everything available there is so much development in catalysis. So, that I can integrate these operations ok. So, some most of the times they call reactive distillation as old wine in new bottle like it is not concept is not new, but can be advantageously applied to many important commercially important systems and we are going to see some examples ok. So, what are the different motives behind application of reactive distillation ok. The first one is to surpass equilibrium conversion we have seen that the first case A plus B giving C plus D the chattel is principal if I if I remove one of the products simultaneously during the course of the reaction, the reaction will shift in forward direction ok. So, I will reduce the recycle cost ok. The methyl acetate example is a best is the best example for this ok. Then the second objective ok selectivity engineering what do you mean by that you have a reaction say reacting system A giving B, B giving C ok series reactions ok and I am interested in the intermediate product B ok right. So, if I can remove this B during the course of the reaction by distillation I can avoid the side reaction of B going to C I can suppress this side reaction of B going to C right and again enhance the yield towards the intermediate products that is selectivity engineering I am going to give you some examples this as well. Energy utilization now that is the main thing you know distillation needs energy ok distillation needs energy and this energy is always given in the reboiler I do not know might have come across some literature where they say that thermodynamic efficiency of distillation is very low because you are giving the heat in the reboiler and not on every stage right. If you do that then your efficiency would go up right. So, if you have so and of course distillation the energy cost is tremendous most of the distillation techniques depending on how much reflux ratio you have right, but in this case since the reaction is taking place in distillation column the reaction is exothermic ok whatever heat liberated will be used in distillation then and there very effective use ok right. So, I do not need to provide extra heat ok in the reboiler the heat is used on that stage itself ok. So, that is that is the advantage of course I if I do reaction separately then I generate steam and can be used somewhere else, but you will lose some there will be some efficiency loss there no heat utilization. So, heat utilization is improved high purity products sometimes some impurities are there very difficult to separate now this is the real separation operation separation in which distillation reactive distillation useful I can react that impurity with something else and that product can be separated very dilute solutions reactive distillation may be useful ok. Difficult separation I told you about this close to close boiling mixtures or isotropic mixture I can add third component and it can form isotope and sorry not isotope another product it can react form that product that product can be separated and you can achieve separation through reaction. Recovery of chemicals the dilute solutions like say high boiling components like lactic acid glycolic acid all these acids which are high boiling acids and if I want to recur them from their dilute solutions. How do I do? Can I use distillation? Suppose I have 90 percent water and 10 percent acid I will have to remove all 90 percent water just to purify it and water is high latent heat compound. So, it is not an economical option. So, instead what I can do is I will react that acid with some alcohol I will form ester I will separate ester which is volatile and that ester can be again hydrolyzed back to acid. So, such schemes are possible with the help of reactive distillation. Longer catalyst life and better temperature control these come together now it is a very important advantage of reactive distillation. If you are doing a reaction in distillation column catalyst is always surrounded by liquid catalyst is always surrounded by liquid and suppose reaction is exothermic what happens normally in a normal reactor reaction is exothermic how much ever effort you put in removing the heat of reaction a slight increase in temperature you cannot really operate a reactor under strictly isothermal conditions. So, that increase in temperature may create some hot spots or heterogeneous catalyst and catalyst may get deactivated. Whereas, if you are doing a reaction in reactive distillation column these hot spots can be avoided. How? Because temperature rise is not possible whatever temperature or other heat is liberated because of the reaction it will be used in evaporating or other vaporizing the liquid and vaporization takes place at almost constant temperature of course, it depends on the composition. But, there will not be drastic rise in temperature or there will not be any hot spots created if you are doing it in reactive distillation column. So, I have uniform it in temperature no hot spot and then because and because of that catalyst life would go up. At the same time there is some deposition of the some unwanted material on the catalyst surface that also is washed away because catalyst is always surrounded by liquid it is the surface of the catalyst is kept clean in reactive distillation compared to gas phase reactions or vapor phase reactions. And, this is a going field this is of course, this we did in 2004 last 3, 4 years we have not updated this. But, this is the statistics of papers and patents of on reactive distillation that tells that see the way it is increasing that tells us so much research going on that many patents coming up. Some old examples now I am going to tell you about different processes in which reactive distillation can be applied. But, of course, these are some old examples I started with solver process where reactive distillation was used for ammonia recovery. And, these are the process where they did not really say that it is reactive distillation the term reactive distillation became popular very recently. And, there are 2 very important examples which made this particular process very popular I will come to that later. Now, esterification, Othmer's work on deutalicity in 1936-1940 there they used reactive distillation any esterification reaction reversible a leisurely principle works well. So, he has reported it long back commercial production of course, started much later propylene oxide from propylene through chloro hydrin process that the first ever process where they what they do propylene oxide formation they do it in reactive distillation column is a bubble cap tray column is the homogenous reaction takes place on the trays in the liquid pool on the trays cracking of di cyclopentadiene all these are very old examples. And, people were using reactive distillation unknowingly without much of theoretical analysis, but quite effectively sodium alkoxide you have alcohol and sodium hydroxide reaction. And, you are removing water of the reaction by toluene right, ethylene dichloride ethylene plus chlorine there is a boiling reactor like. So, you remove heat of reaction there right. So, let us come to the first example which is a very popular example I like to show this before I talk about reactive distillation and I have told you many times methanol plus acetic acid giving methyl acetate and water. And, this is a conventional process this is a conventional process in which you have a reactor and followed by see how many columns 5 plus 4 9 columns. Of course, there are many versions of this process sometimes people use even 12 13 columns right. Why? If you get that residue curl map for the system see when the reaction takes place you have a cotonary system methanol because there is a reversible reaction right in methanol, methyl acetate unreacted methanol rather methyl acetate water and acetic acid. So, 4 components that is a nice problem for conceptual design 4 components and many azeotropes form right. And, these azeotropes will make the separation difficult many means there are 2 azeotropes methanol methyl acetate and methyl acetate in water. And, because of that separation is very difficult in fact acetic acid water separation is also a problem I told you it is close boiling mixture that is why you see many columns here azeotropic column extractive distillation column then you have washing you have to recover your solvent recycle it back. So, many things. So, reactor followed by so many columns you can imagine it is a big plant right. And, look at this they have converted the entire plant or as I said they have condensed the entire plant in a single unit where you have acetic acid going in at a top the column methanol going at a towards the bottom of the column because it is volatile no it will move upward and acetic acid will go down right. So, you will have better contact of these 2 reactants at the top you get methyl acetate here you get water. So, they use sulfuric acid homogeneous catalyst of course, that acid will also come along with water and that can be recovered later right. But, otherwise you have just 1 unit right separation one otherwise difficult why how you can achieve all this here because azeotrope is broken when the reaction takes place right extractive distillation in effect is also achieved here by adding acetic acid in the non-reactive distillation region rectifying section. And, the entire design all the details are available in literature if you want if you are really interested in it. But, and this is a commercial process this month's process it is a commercial process ok. So, you have reduced the entire plant or you condensed entire plant in single unit so much reduction in energy capital cost right recycle. Another important example which along with a methyl acetate made the reactive distillation very popular ok. Methyl acetate and this MTB process these 2 processes the commercial process started in 1981-82 ok. From that time onwards about last 25, 26 years this particular field is so much research going on. MTB you know the application of MTB right it is used as octane booster in gasoline or petrol rather ok. And, it is made from methanol and isobutene made from methanol and isobutene is again a reversible reaction reversible reaction right catalyst use is cation exchange resin. Typical reaction conditions about 15 atmosphere pressure and temperature 60 to 100 because the temperature changes in the column right this is a flow sheet ok small flow sheet where you have you do as much reaction as possible in this reactor ok. And, then you have equilibrium mixture that goes to the reactive distillation column it is not that I am doing the entire reaction in reactive distillation column right. I am doing reaction in the reactor first and a mixture goes out and acts as a feed to the reactive distillation column. See the color code I am using red is reaction blue is distillation ok. Now, in this case why will I do the reaction first here why cannot I do the reaction entire reaction distillation column any advantage doing that why do I actual commercial process they do it this way ok. This is supposed to be the best option do it instead of doing the entire reaction in the distillation column. Conditions they are matching anyway you know like since the reaction is taking place here right increase the you know speed you can increase here as well know. In fact, if you remove one of the products that is what I am doing. So, the reaction will go in forward direction as a practical advantage in this ok. Yeah, if you do the reaction in the column the column size would go up and reactive distillation column is in terms of its fabrication column internals it is much more expensive compared to a normal vessel this is just a vessel or it is a fixed bed reactor probably ok. Here you use very special packing which is a catalytic packing and which is quite expensive. So, reduce the load on this particular column you do as much of reaction as possible here till you go to equilibrium and remaining conversion or further enhancement is done in reactor distillation column and that is the technique normally used in many other processes ok. So, that you reduce the burden on reactor distillation column because this is not only expensive, but also difficult to design right. So, something goes wrong here should not affect the entire performance already you have got some conversion ok. So, for example, in this case I go from 98990 which is equilibrium conversion up to 99 percent see with reactive distillation I get about 99 percent conversion. Now, another important point see why I am doing this reaction reactive distillation column because MTB can be separated from the bottom ok. So, as the reaction takes place as the reaction takes place MTB is separated. So, it ships in forward direction ships in forward direction. Now, this isobutene is not available in pure form isobutene comes along with C4 stream right C4 stream from refinery it has N butane isobutene right. So, many other components and along with that you have isobutene and I just want to use this isobutene for reaction right. So, I am using C4 because otherwise the separation of isobutene from C4 is not so easy ok. So, I am using C4 I am using methanol I am doing this reaction isobutene from C4 will react ok. So, in this configuration I have C4 coming out from the top volatile unreacted C4 like N butane isobutene, butene is linear butene is and all right and then MTB from the bottom converging is almost 100 percent ok. Now, look at the boiling points look at the boiling points isobutene is the most volatile right MTB is the intermediate boiling and methanol is the least volatile right. Now, the mole ratio that they use in this reaction slightly excess methanol ok 10 percent excess 5 percent excess ok. Now, you have some unreacted methanol should come out right from these two streams ok which stream it will come from either this or this MTB from the bottom why because this is right ok. Now, again you are going by just boiling points that is why you give that reason or the answer it is ideal, but it is not ideal that is what I want to say it is not ideal in this case is a non ideal system. So, methanol forms azeotrope with C4 a minimum boiling azeotrope a minimum boiling azeotrope and then because of that it comes out from the top ok. You can plot a residue curve map for this system and you will realize ok that there is a azeotrope between C4 and methanol which is a minimum boiling azeotrope ok. That is why MTB comes out methanol has a tendency to go up it becomes volatile ok. So, if you just go by boiling points you will see you will say that ok reactive distillation may not be useful here because your product is intermediate boiling how can I separate right. But methanol being volatile under those conditions even if by boiling point is less volatile because of presence of C4 it is volatile it has tendency to go up in the column. I can separate pure MTB from the bottom ok that is the logic and that is how reactive distillation works ok. Very popular process in fact this is this process is responsible for the further research in reactive distillation boosted reactive distillation work in reactive distillation rather ok. Very famous and most of the commercial brand of about 50 percent of MTB is produced by reactive distillation technique ok. Another example this is something that we worked on reversible reaction methanol plus formaldehyde giving methyl alcohol plus water reversible reaction like esterification this is acetylization reaction and this product is highly volatile ok. So, you can do the reaction reactive distillation column and these are our research this is our research work and you can see the enhancement ok. If you even if you reduce the methanol to formaldehyde ratio from 6 to 3.5 you get enhancement in conversion you can reach close to quantitative conversions all right. Now, there are many other examples this is again an interesting example which we have also working isobutene to diisobutene. Now, isobutene is see as I said it is it again goes to formation of or manufacture of MTBE right, but then of course, the people are talking about ban on MTBE right because of its solubility in water and all that right. So, there is another alternative to MTBE that you can dimerize the isobutene and form diisobutene and this diisobutene if hydrogenated gets converted to iso octane and this iso octane can be a fuel additive ok. So, it can be a replacement for MTBE to some extent of course, it cannot match the octane number and other properties of MTBE, but to some extent it can replace isobutene MTBE because its octane number is 100 isobutene sorry diisobutene or iso octane octane number is 100 right. Now, what are we doing here? We are doing dimerization saturation and dehydration reaction in the reactive distillation column this is one patent that talks about this ok. Of course, I do not know whether a commercial process is available or is working on this principle or not, but what I am trying to do is passing C4 it is going up and dehydrogenation section the isobutene from C4 gets converted to isobutene right and when it when the steam goes up this isobutene gets converted to diisobutene right and this diisobutene being high less volatile falls down. This is a section of distillation column is a rectifying section of distillation column diisobutene falls down and then it can be collected from the bottom of the distillation column C4 goes up ok. Now, there is a very a peculiar system where we are trying to use reactive distillation ok to enhance the selectivity right. How will you increase the selectivity? In a normal reactor once the dimerization takes place the dimerize a tendency to react again with diisobutene and gives you trimer then you get tetramer and all that. In normal conventional reactor like CSTR or plug flow reactor because your product is there in the reactor. Now, since you are removing that product that is your dimer ok you are increasing the selectivity you are suppressing the side reaction. It is possible to do saturation also simultaneously you can pass hydrogen and if you have a bifunctional catalyst which catalyzes hydrogenation then your diisobutene gets hydrogenated to isoctane which is a desired product. So, you can have all the reactions taking place in reactive distillation column of course, this is an idea which was patented I do not know whether commercially practice or not mostly answer is no. But I am talking about a possibility you can have not just one reaction taking place in the column you can have multiple reactions taking place in the column very interesting case. So, they claim that there is a less equipment cause less recycle cause better selectivity that is what I told you. The general name for this is reactive dibuteneizer where you are removing isobutene and make converting it to isobutene isobutene is converted to diisobutene. So, both isobutene and isobutene are removed from the C4 streams that is why it is dibuteneizer, dibuteneizer. This is another example nylon 6-6 is a very famous reaction adipic acid plus examethylene diamine giving polymer that is the adduct rather plus water. No one can imagine polymerization having conducted in reactive distillation. Of course, we do not do polymerization in the column cause you will have practical problem the polymers, choking and all that right. That is why it is done in a large hold of vessel this is your reactor the red color this is your reactor your reactants are going in and water is separated and this water separation is very crucial. And so, this is not a new technique in fact, nylon process is very old and ever since as far as I know ever since its practice the water removal is done like unless you remove water the polymerization reaction would not get going and if you want a high molecular weight product or a nylon of required quality nylon 6-6 water removal should be quite efficient. So, this again uses reactive distillation principles right. So, improved conversion because of water removal and selectivity can be improved by efficient removal of water. When I say selectivity in polymerization I talk about the quality of the polymer in terms of molecular weight because it is quite possible that you say nylon 6-6 you may have different types of nylon 6-6 forming depending on their molecular weights. But I am interested in a very narrow range of molecular weight exact what is required in that case the water removal is very efficient it should be very efficient. So, reactive distillation again C5 streams I talked about C4 in refinery now I am going to talk about C5 the C5 stream normally goes to gasoline or sometimes they make TAME out of it that is tertiary amyl methyl ether which goes to again gasoline. So, C5 stream has some dynes dynes means two double bonds and they will really these are very reactive compounds and they will create problems later on if you do not separate them. So, these dynes are hydrogenated and they will form olefins right and olefins also can react with mercaptan now mercaptan also not desired right mercaptan is a compound with sulfur in it and that is not desired if you are letting this C5 go to gasoline right. So, this is to be removed and this removal can be effectively done with the help of reactive distillation. So, these compound it is olefin sulfide which is a high boiling component once this is formed in the reactive distillation it can be separated simultaneously because of its low boiling high boiling point right. So, we exploit this reaction and remove olefin sulfide during the course of the reaction by conducting the reaction in reactive distillation column. So, this particular diagram shows how we convert the conventional process how we can convert a conventional process to a reactive distillation process and a multiple reactions taking place here again it is a patent and I do not know whether the commercial process exists or not, but again the idea is to rather show the possibility of we are doing several reactions in a distillation column. In the first zone once the hydrogen is introduced this is a section of distillation column once the hydrogen is introduced you have desulfurization taking place mercaptan plus olefin giving olefin sulfide this olefin sulfide falls down. So, the reaction shifts in forward direction hydrogenation this particular reaction takes place in this particular section then you have isomerization also you go for required C5's they are very particular C5's that which are important in C5 stream they react with methanol later to form TAME. So, you can do isomerization of this C5 streams itself the many isomers of C5 you get a desired isomer. So, that can be done in the reactive distillation column otherwise if you look at a conventional process you have caustic addition to remove sulfur then you have hydrogenation, hydrogen compression. So, everything can be all these steps can be combined in reactive distillation unit and you can have reduction in capital cost. Now in this particular case your C5 going in and then after all these reactions I have required C5 without sulfur here and this required C5 or a desired isomers of C5 can be made to react with methanol to form TAME. So, I can have another section here in the distillation column itself. So, you react that C5 with methanol which will form TAME which can be separated from the bottom of the column. So, you have 4 reactive distillation zones in a distillation column. Of course, it looks quite ambitious, but then it is possible to do it. Theoretically it is possible and of course, the advantages that they have claimed are high conversion, low catalysts life then the reactor function is not confined to pure reactant systems. You can use even a mixture energy utilization. So, remember I have talking about various motives behind the applications of reactive distillation. So far we have seen how reactive distillation can be used to enhance the conversion, it can be used to enhance the selectivity. Now I am going to talk about another example where you have reactive distillation being used for energy utilization and it is used for increasing this selectivity as well in just one process and this process is making ethylene glycol from ethylene oxide EO2 EG. So, this is the process and by doing this again C, A plus B giving C and C plus A giving D. So, it is a series parallel reaction and if I remove this product simultaneously during the course of the reaction, then I can surprise the side reaction. This is second reaction is side reaction. So, as and when this ethylene glycol is formed, it has to be removed and distillation column helps me do that. I have I have surprised the side reaction. Again look at the heat of reaction very high and I can use this heat in the column itself. So, energy utilization. So, like this I have many examples. We can use energy of alkylation. Now this reaction is for cumene production, cumene famous process for phenol manufacture which uses benzene plus propylene giving isopropyl benzene then isopropyl benzene that is nothing but cumene and this cumene then on hydrolysis or other then cumene is oxidized to cumene hydroperoxide and this hydroperoxide and hydrolysis gives phenol and acetone. That is the process. So, the first part it is alkylation part can be performed and there are patents and I think it has been commercialized can be done in reactive distillation column. And it is again highly exothermic reaction and you can use the heat of reaction to for distillation right. And here you are increasing the selectivity as well because you have other products formed. See benzene plus propylene giving cumene at the same time cumene plus propylene can give you diisopropyl benzene, triisopropyl benzene and so on. So, this multi-alkylation can be suppressed. So, again advantage in terms of selectivity improvement. This example we have done this in our lab as well. Acetone giving the acetone alcohol and miscellaneous oxide again it is A going to B going to C type reaction increasing selectivity. These are all commercial examples commercially important example chlorinations for that matter. If you are doing chlorination of any hydrocarbon you have many products formed like monochlorinated, diachlorinated, trichlorinated. So, again it is a selectivity issue that you if you remove monochlorinated as and when it forms I can avoid diachlorinated product I can avoid trichlorinated product right. So, the many examples I have given here close boiling mixtures I told you difficult to separate. Cyclohexene, cyclohexene boiling point difference is just 1.5 degree centigrade right. This particular mixture you come across in the process for manufacture of cyclohexanol ok. So, benzene partial hydrogenation to cyclohexene and you get a cyclohexene as a side product and separation is required for cyclohexene to further get converted to cyclohexanol right. So, this separation is otherwise very difficult. So, what we do cyclohexene can be made to react with acetic acid or water and corresponding product. What is the product? Acetic acid will form cyclohexyl acetate with cyclohexene or if it is water it will form cyclohexanol and all both these products are high boiling. So, these products being high boiling can be easily separated in react to distillation column right. So, otherwise separation was difficult, but since we form cyclohexanol which is high boiling, the boiling point difference in cyclohexanol and cyclohexene is much higher right. So, separation is possible. Now, the question is what will you do with the cyclohexanol? Cyclohexanol as a market right it goes to nylon caprolactam. So, I can use the cyclohexanol, I can sell it as it is otherwise if it is cyclohexanol acetate does not have much market. So, what will I do? This is a reversible reaction, I will hydrolyze it and convert it back to cyclohexane and acetic acid and acetic acid will be recycled back. So, it is like azeotropic agent getting this is recycled back or extractive distillation where solvent is getting recycled back similarly here your external component will be recycled back. Same is true for orthozylene paralleline very famous separation of course, this is again not commercially practiced. There is a famous process by UOP Parex which is used for separation, but it has been proved that we can do alkylation and the alkylated product can be separated and reactive distillation is theoretically possible. Same example MTB you have C4 and so many components I have told you about it and I am interested in isobutene, I am interested in isobutene. Rest all are all C4 and there are isobers normal distillation would not work, normal distillation does not work. Will you go for azeotropic distillation? That also has a problem because if you use some component which forms azeotrope with isobutene the same component will form azeotrope as well. So, this selective azeotrope formation is not possible here. So, azeotropic distillation also can be used for this extractive distillation also not possible. So, the best way is to exploit the difference in reactivity azeobutene has much higher reactivity compared to other components. So, what they do they use C4 and make MTB out of it. So, MTB even if you are not interested in making MTB as such as a product this reaction can be used to separate azeobutene from C4 and then MTB can be further cracked or de-etherified to azeobutene and you get pure azeobutene then. So, that is one way of separating azeobutene from C4 mixture. The recovery of chemicals I have given many examples here lactic acid and ethylene propylene glycol from water, formaldehyde recovery from through acetylization these are all dilute aqua solutions and as I told you before otherwise the separation is very expensive you have to remove water which is a high latent heat component and is highly energy intensive process. But if you use reactive distillation and can you react this component with some alcohol or olefins in that case you make volatile components which can be separated very easily and they can be hydrolyzed back to the original component right. Acetic acid can be recovered so much work that we have done here for recovery of acetic acid from dilute aqua solution through esterification. Many examples I have given the references also. Yeah, last example which is quite interesting I thought I will include this in my presentation it is from literature only. This is for making hydrogen you must have heard about fuel cells hydrogen they run on hydrogen reaction of hydrogen and oxygen giving water you have chemical energy converted to electrical energy very clean way of using energy right. Now, this hydrogen where will you get it from? You need hydrogen where will you get it from? And suppose you want to run a car using fuel cell right. So, you have on board a fuel cell which will need hydrogen. So, will you fill your car with hydrogen? Difficult right that I have how much compressed hydrogen you can have and it is not safe also right. So, the best way is to generate hydrogen on car itself on board ok. They are talking about having a reformer. Say you feed instead of petrol you use methanol and methanol is reformed or converted to hydrogen ok and CO2 that hydrogen can be used to use in fuel cell that is one way of looking at it. Otherwise see the problem is storage of hydrogen. Suppose I have a hydrogen somewhere I have a hydrogen tank in my chemical plant I am coming as side product. The question is how do I use that hydrogen on car on board rather right because I cannot have hydrogen gas storage. So, this is one way of doing it a very clever way decalene this is chemical structure and its unsaturated form is naphthalene and this is your hydrogen. If you hydrogenate this naphthalene molecule the reaction is reversible of course, it takes place in the presence of catalyst platinum carbon ok. If you hydrogenate this compound you get this compound and this reaction is reversible. Can I explore this reversibility? Now instead of filling my car with hydrogen I will fill my car with decalene ok right and this decalene on board will be dehydrogenated to get naphthalene and hydrogen ok right and that hydrogen will be used in fuel cell. So, what did I do? I have used this compound. So, its volume is much less compared to hydrogen ok. So, I use this compound I will fill my car with this and then generate hydrogen on board ok that is the idea and this is that graph ok. In terms of gravimetric contained and volumetric contained this particular option falls somewhere here. That means for the same gravimetric contained you have sorry for the same volumetric contained you have so much gravimetric contained and this is something recommended by DOE that is Department of Energy USA that you should have your compound somewhere here or your not compound or whatever way of using hydrogen should be somewhere in this region then only it is going to be economical. So, they have shown that if you use this option you are somewhere here. So, for the low volumetric contained you get very high gravimetric contained or is other way round low gravimetric contained you get very high hydrogen sorry low. So, that is the that is the advantage of going for this particular scheme. Now, where is reactive distillation here? Where is reactive distillation here? This reaction is from reactive distillation mode is a reversible reaction right and this is small tiny reactor a thin film evaporated type reactor they have demonstrated and simultaneous removal of hydrogen helps the reaction get going in power direction and you can get effective production or the enhanced production of hydrogen on board right.