 we will learn the partial oxidation method for hydrogen production. As the name suggests partial oxidation means substychometric amount of oxygen being reacting with the feedstock to produce the sin gas. Now the reason for this substychometric use of oxygen is that the complete oxidation can result into carbon dioxide and water and we will not be able to get the desired product which is hydrogen. The delta H value suggests that this is an exothermic reaction. The partial oxidation of hydrocarbon here in the reaction is mentioned for methane to produce sin gas is an exothermic reaction and this can occur in the presence of oxidant. It can be oxygen or air. This is faster than the steam methane reforming because the react operating conditions are very high temperatures and the reaction kinetics are favored under those conditions. The H2 by CO ratio which is obtained is 2 ideally it is 2 looking at the reaction however in real practice it lies somewhere around 1.6 to 1.8 which is less than SMR process. In SMR partially the hydrogen is coming from steam which is not the case here in partial oxidation. Carbon dioxide is released which is higher in amount and the method can be utilized wherein the requirement of H2 by CO ratio is lower. If the content required of hydrogen is lower in those processes it can be specifically used. Now the partial oxidation which is represented by POX can be either a non-catalytic process or it could be a catalytic one. In non-catalytic the reaction condition is such that the temperature operating temperature is high 1200 to 1500 degrees centigrade and the feedstock which is used can be any from gaseous to liquid to solid feedstock. So there is a fuel flexibility wherein any type of feedstock can be used. Generally in refineries where the bottom of the barrel fuels needs to be upgraded because they cannot be used because of the emission norms and they have high amounts of impurities like sulphur impurities or heavy metals or olefins as such they cannot be used as such. So they can be upgraded using this particular method. With the use of catalysis catalyst the operating temperature can be lowered down and this roughly lies in the range of 600 to 900 degrees centigrade. Usually lower hydrocarbons are used for catalytic process. Using with the non-catalytic partial oxidation name suggesting that catalyst is not used as such that temperature required will be higher. Now the fuel flexibility means natural gas which cannot be used using SMR process because there is a variety of hydrocarbons present in the gaseous form or because the content of sulphur is higher or liquid fuels like heavy residual oils or pet coke, coal all the feedstock can be upgraded can be used for hydrogen production using non-catalytic partial oxidation. Since there is no catalyst so the catalyst deactivation challenges or problems are not there. We can use either air or oxygen as the oxidant however that use will depend upon what is the reactivity of feedstock which is used. If the feedstock which is used is has a low reactivity oxygen would be preferred. Also it depends upon what is the end use application. If the end use application desires high purity of hydrogen in that case oxygen could be used as an oxidant. However if the end use application is wherein certain amount of nitrogen is acceptable like for ammonia production then air can be used as an oxidant. In that case the outlet hydrogen stream will have nitrogen which can be used directly for fertilizer industry. The operating conditions are 1200 to 1500 degrees centigrade temperature, a higher pressure of 50 to 80 bar at max to 80 bar. The H2 by CO ratio which we will obtain from partial oxidation that depends upon what is the composition of the feedstock which is used and also how much is the amount of steam which is added to the process. There are two processes which are patented, Texaco, Syngas generation process and Shell gasification process however these are almost similar. The major difference lies in how the gas is being cooled, waste heat recovery unit as well as the design of the nozzle and the removal of soot. This particular method could be best suited when the end products of the refinery or the low value fuels needs to be upgraded and the process H2 by CO ratio since it is lower in this case. So, this Syngas can be used for fissure drop fuel synthesis or for methanol synthesis. There are large number of reactions that can occur in non-catalytic partial oxidation. The first one, this is hydrocarbon on partial oxidation giving Syngas. The first reaction is the partial oxidation reaction. Second one is also a partial oxidation reaction however if the fluid, if the fuel is contaminated with large quantities of sulphur, in that case under the reducing conditions it will form H2 S. Hydrocarbons, they can also undergo reforming to produce syngas. So, the third reaction is the reforming reaction, carbon dioxide which will be formed in the process can also react with the hydrocarbons to give syngas. So, this is the dry reforming process and these higher hydrocarbons under the conditions operating conditions can crack to give carbon, lower hydrocarbons and hydrogen. Besides these reactions the carbon which will be formed in the process can undergo partial oxidation to produce CO, it can undergo gasification to produce syngas and water gas shift reaction can take place in the non-catalytic partial oxidation process. To understand the entire process well, let us see the process flow. If oxygen is used as an oxidant in the process it has to be produced using an air separation unit wherein the atmospheric air could be used to separate out oxygen from the rest of the compounds, rest of the elements. Now this oxygen along with the feedstock and steam is used as the input for the partial oxidation reactor. If heavy oils, heavy residual oils they are used they needs to be preheated, they need to be atomized and then fed along with steam to the reactor along with oxygen. Here in this is a special reactor wherein the oxidation of the reactor feedstocks along with the oxidant takes place in the burner region followed by the rest of the reactions. So that operating condition inside the partial oxidation reactor we know it is high pressure and high temperature conditions which leads to metallurgical challenges and as such the vessel is a high pressure vessel which is a brick lined reactor. Once these reactions occur inside the partial oxidation reactor, syngas is formed and depending upon the feedstock there would be several particulate matter, soot will be formed in the reactor using steam that can be scrubbed off and that can be collected. So the waste water along with the soot could be recycled, the treated water can be again fed back to the partial oxidation reactor and the soot can again be fed back to the partial oxidation reactor. After the syngas is being produced by the process this is at a high temperature this needs to be cooled down before it enters into the shift reactor. So this temperature difference can be used for generating steam after it has been cooled in a syngas cooler the temperature of the syngas is about 340 degree centigrade and this can be fed to a carbon dioxide shift reactor wherein with the help of steam the carbon monoxide will react with steam to produce carbon dioxide and if the feedstock is rich in sulphur impurities then we will also have under the reducing conditions we have H2S. So both the acid gases needs to be cleaned, H2S and carbon dioxide these needs to be removed either in two step method or it could be in one step method earlier you plans they used to have two step method wherein H2S was removed prior to the shift reactor as that can sulphur impurities can poison the shift catalyst and thereafter the carbon dioxide was removed in the later part however in the modern plans an integrated acid gas removal is done where both the acid gases are removed in one step first H2S is removed using various solvents methanol is most widely used of solvent the cold methanol is used to first separate out H2S the sulphur could be sulphur obtained could be fed to the clasp plant and finally an elemental sulphur could be obtained that could be used for various applications carbon dioxide is again removed using the solvent removal method and that carbon dioxide which is obtained can be can go for carbon capture use and sequestration small amount of other impurities which are left out in the hydrogen outlet stream can further undergo purification step to get pure hydrogen. Now in the entire process steam is added and that plays multiple roles so steam is added to not only reduce the carbon formation in the process in the water gas shift but it also after cooling it has substantial amount of steam in the sin gas that can undergo water gas shift reaction. It also acts as a moderator since the operating conditions are very high temperature in the partial oxidation reactor there can be hot spots and uncontrolled reaction leading to very high temperatures and that can be moderated with the help of steam it also is used for it is also being used for quenching the suit which is formed and the cleaned and the other particulate matter. So this is how the entire process is. Now as we have mentioned that the reactor which is being used for non-catalytic partial oxidation reactor so this is a brick lined reactor wherein there is a burner region to which the oxidants is being fed. So that is the flame region wherein partial oxidation reaction occurs and thereafter is the heat exchange region process. Since there is no indirect heat exchange involved by indirect heat exchange we mean in SMR we had externally heated reformer tubes which were heated by means of burners here in within the same reactor the flame the combustion of the oxidation of the reactants produces the desired reaction temperature. So there is no indirect heat exchange here involved in the process the heat recovery is poor and the heat losses are more as such the thermal efficiency of the process is lower. But since the reaction conditions are very high temperature conditions so the kinetics of the reactions are faster the convergence are better so the methane conversion achieved in the process are high. Compared to SMR since the heat exchangers involved are number of heat exchangers are less as such the design becomes compact simple and the reactor is less expensive. If we see the efficiency of the process this is somewhat between 60 to 75 percent. However the hydrogen which is being produced in the process is lower in content energy efficiency 15.9 to 19.3 mega joule per meter normal meter cube and this is an important process in the refineries. If we look at the catalytic partial oxidation then catalyst with the use of catalyst we can lower down the operating temperature from 1200 1500 degree centigrade to 900 degree centigrade and with the use of catalyst the selectivity towards the product which is hydrogen in our case improves. Most of the reports are on catalytic partial oxidation of methane however C2 plus can also be used higher hydrocarbons can also be used but they may have problems associated with the catalyst poise deactivation. It is found that the selectivity towards syngas formation and a higher methane conversion could be achieved at temperatures above 750 degree centigrade. Along with the major reaction which is the partial oxidation of methane to give syngas there are a large number of competing reactions that can also occur in the process like the dry reforming of methane to produce syngas. Water gas shift of the carbon monoxide to produce hydrogen and carbon dioxide. The Baudard reaction wherein carbon which is being formed reacts with carbon dioxide to give CO, combustion of methane can occur giving carbon dioxide and water, combustion of CO to give carbon dioxide, combustion for hydrogen to produce water. Now which of these reactions will occur? The equilibrium state will be decided by the equation these equations and hence that will also decide how much percentage of methane conversion occurs, what is the product selectivity, what is the yield of hydrogen which could be obtained in the process. There are, if we try to explain the catalytic partial oxidation mechanism, it is a very fast reaction with a very small residence time. It is very difficult to exactly identify the mechanism but there are two postulates. One is a direct mechanism occurs wherein the methane it dissociates on the surface of catalyst. So we have a support having catalyst. So the methane it dissociates on the catalyst, carbon getting adsorbed, hydrogen also getting adsorbed and then oxidation occurs by molecular oxygen which is present on the catalyst surface. So the oxygen which is on the catalyst surface this reacts with the adsorbed carbon on the surface to give CO and the hydrogen adsorbed they combine to form hydrogen molecule. So as such it is expected that methane on the surface of the catalyst gets adsorbed dissociated into carbon and hydrogen both of which gets adsorbed. This adsorbed carbon combines with the surface oxygen to produce CO and the adsorbed hydrogen combines with another adsorbed hydrogen to give hydrogen molecule. This is the direct method of catalytic partial oxidation. The indirect method which is known as combustion and reforming reaction, this is a two-step method. Initially methane undergoes combustion reaction to produce carbon dioxide and water. Methane undergoes reforming to produce syn gas in the process and first one being an exothermic process, second one being endothermic process. It can lead to hotspots or uneven temperature distribution inside the reactor. So these are two reaction mechanisms which are proposed for catalytic partial oxidation. Again when it comes to catalytic partial oxidation catalyst has the major role. Catalyst we have already studied in great detail about the characteristics which catalyst should have what are the requirements in terms of catalyst support and promoters. In catalytic partial oxidation we can you have either noble metals or non-noble metal is called catalyst or various other options. The noble metals they are good in the sense that they provide good conversion and they have higher reactivity. They have higher selectivity towards the product. Platinum on alumina support was the used in catalytic partial oxidation and it is known to have a good activity. But the major problem associated was that of sintering. So at higher temperature sintering was observed. However this could be improved if cerium zirconium could be used as a promoter and that can reduce the problem of catalyst deactivation. But the major challenge remains is the cost here and with all the noble metals the cost is the major issue towards commercialization of overuse in the industrial scale processes. If with platinum like for example the cost is although the cost remains volatile it is approximately 30,000 times that of the nickel. So that needs to be that is the major obstacle. However higher loading is also required higher than 1% about 1.5% loading is required that again is a disadvantage. Lodium on cerium oxide alumina is a good catalyst wherein the loading percentage of Lodium compared to platinum is lower. It is found that the how the catalyst is being synthesized that has a effect on the entire process like if the catalyst is synthesized using some of the techniques which are low temperature methods wet impregnation in that case they work well under the lowered operating conditions. However at higher operating conditions they are prone to more sintering. Lodium it is comparatively less expensive among the noble metal catalyst but it is not stable and it gets deactivated. The reason it is found in different oxidation state so and there is transition between the different oxidation state sometimes it is irreversible. As such the activity it is not recovered in the process but this was found to improve when alumina support was used for the Lodium catalyst. So with all the noble metals the major bottleneck lies is the cost and reducing the cost could be done another possible option could be that these can be combined with other metals which are less expensive or can noble metal non-noble metals can be used. Non-noble metals definitely have a lower activity have a lower conversion compared to the noble metals but the advantage they enjoy is that they are less expensive. Among the non-noble metals nickel is the most widely studied one and it has a high activity as well as better conversion but the problem that nickel catalyst phase is the sintering and deactivation with the nickel when it is supported on alumina then it reacts with the support. So nickel on alumina we have also seen in SMR this is used as a combination is used for the SMR catalyst as well but nickel it interacts with the alumina to form NiAl2O4 and it loses its activity. There are other supports which also are studied like nickel on Siria or LA2O3 and among the two separately if we are using them as support however combined one being used as a support CIO2 and LA2O3 it has it is less prone to carbon formation. Nickel it exists in various oxidation state and any oxidation state higher than 2 equal to 2 or more they favor complete combustion rather than the partial combustion. So here in the dispersion how it is dispersed with different activation oxidation states how it is being synthesized what are the support properties all these affect the activity of the catalyst copper having a lower less expensive but it shows catalytic activity lower than nickel and also it can be used for only lower temperature because of the lower poor thermal stability at higher temperature however that can be addressed if it is supported on alumina catalyst other than that the other supports which were which are studied are zirconia silica and titanium iron and cobalt they also perform better but they and they are at the same time they are less prone to deactivation and sintering and they form metal oxides with multiple oxidation states Fe2O3, Fe3O4, Fe FeO are found to be like some of the oxidation state these perform better compared to the other oxidation state and these can be on the various support like alumina magnesium oxide or TiO2. Now in summarizing the non-lobal part it is the method by which catalyst is being synthesized and that has an impact on the activity of the catalyst how it is going to interact with the support and how is the thermal stability is it prone to deactivation or sintering or not. So, all these are dependent on how it is being synthesized what is the size what is the shape of the catalyst what is the surface area. So, there are many factors which influence the conversion selectivity as well as the activity the option could be to reduce the cost at the same time to improve the activity use of bimetallic catalyst. So, we can combine noble and non-noble metals in such a way that noble metals are coated onto non-noble metal which is used in the core. So, a core of non-noble metal and a shell of noble metal wherein we can reduce the use of noble metal we can decrease the cost at the same time we can have the benefit of using noble metal. Other catalyst like perovskites they also show good activity and stability and they are less prone to carbon formation. So, like the AB03 in ABA position LA on B position iron copper nickel cobalt they have good catalytic activity and they show good conversion at the same time selectivity. To summarize this part we have seen both the catalytic and non-catalytic partial oxidation non-catalytic partial oxidation the biggest advantage is the fuel flexibility any fuel can be used with the catalytic oxidation. However, the operating temperature gets lower down compared to the non-catalytic partial oxidation the residence time is small as such when it comes to partial oxidation the heat transfer and mass transfer could be a problem and there could be hot spot which could be formed in the reactor. The gas composition which is obtained after the partial oxidation it depends upon factors like what is the feedstock composition. Thermodynamics is going to play important role in determining what is the gas output and the catalyst which is used. So, the catalytic partial oxidation this is compared to SMR requires a smaller footprint it is it can be in a modular construction it is simple to operate we can use the other fuels as well other than methane and it can provide because it is a modular operation. So, it provides a flexibility in production capacity the capital cost requirement is lower and the energy consumption is lower because it is an exothermic process. However, there are challenges with the partial oxidation process like the life span of the partial oxidation is lower and these are the obvious regions when you are using catalyst they are prone to carbon formation and sintering. If we want to use if we want to use air as an oxidant then the outlet gas stream will be diluted with nitrogen else we need to use oxygen and then we will require air separation unit that will add to the cost of production. Since we are this is the oxidation method and it is an exothermic reaction the gases they react explosive they can react explosively and we have to operate outside these explosive limits. So, extreme hot spots highly elevated temperatures needs to be avoided. And the catalyst and oxygen carriers so still there the cost of the the cost the thermal stability the conversion and selectivity. So, appropriate catalyst support needs to be which is also at the time economically viable is required for efficient and stable operation of partial oxidation. Thank you.