Final Process DescriptionHydro-treating and Separation MethodHydro-treating is a method used in making renewable diesel. It is a process to remove the hydrogen in triglycerides and to saturate double bond in carbon. This process refers to production C15 to C18 hydrocarbon having the properties like diesel oil from petroleum oil. It makes the product can substitute diesel and named as renewable diesel or green diesel.There are two methods in making renewable diesel, hydrogenation and decarboxylation. Both of them react with triglycerides and produce hydrocarbons of different molecular weight. Hydrogenation only produces propane and water as by-products. Decarboxylation produces the same amount of propane as the hydrogenation pathway, but it also produces CO2.The hydro-treating have a significant impact on the processing conditions (usually H2 input) and on the output products. Catalysts can be used to control the reaction pathways that are followed. Both HDO and DCO will take place during hydro-treating and cannot be completely controlled. Although, we have to choose what the reaction pathway happened in that process.We prefer choosing reaction of hydrogenation reaction than decarboxylation. Although hydrogenation needs hydrogen more than decarboxylation, the other product is water. We can use water as our utilities in our plant. It will reduce our cost in production. If we choose decarboxylation, by product is carbon dioxide. We cannot use carbon dioxide, so we only release the carbon dioxide to atmosphere. There is another reason in choosing hydrogenation because there are an existing plant choosing this reaction pathway named as Neste plant. It makes sense if we choose this methods because there are existing plant than choosing the other pathway which is theoretically could be happened but there are no existing plant. In controlling the reaction, we used catalyst to fastener the reaction. We used sulfide Ni/MO We used sulfide Ni/MO y-Al2O3. With this catalyst the process of hydrogenating and decarboxylation will be happened simultaneously. Nickel prefer to go to decarboxylation reaction and Mo prefer to select the hydrogenation reaction and the combination of them will make the Alumina has a function as a catalyst support. Support is a component in order to enlarge the surface of catalyst by the catalyst porous. Alumina is used because the price is economically enough, have a stability in structure and the size of porous can be vary. This support is relative stable in high temperature, and have higher melting point and suitable to react with hydrogen. (Zhong He, 2012).Nickel is metal used as a catalyst component in a lot of hydro-treating process. This metal is chosen because it have higher melting point and it can be used in exothermic condition. Using this catalyst will produce same or higher yield than using noble metal as a catalyst. (Dindi et al,2008). This metal, Nickel, is selective with decarboxylation reaction, but Molybdenum is catalyst selected in choosing hydrogenation reaction (Vonortas et al, 2013). Another reason in using this catalyst because the catalyst have a high conversion. The conversion of triglyceride using the catalyst is 100 percent. It means all of triglyceride is react with hydrogen and convert to water, biodiesel, and carbon dioxide.After the hydro-threating, the products are water from hydrogenation, carbon dioxide from decarboxylation, green diesel, and gas. We have to separate them using 3 phase separator. The carbon dioxide will go up base on the gravitation. The gas will process again before releasing to atmosphere. We use absorber to separate carbon dioxide and hydrogen in gas phase. Hydrogen is used again as feed at hydro-treating reactor. The water will be used as our utilities like feed water for steam generating. The green diesel formed consist of another hydrocarbon like propane. In separating propane, we use stripping column than depropanizer because depropanizer needs more energy for generating reboiler and condenser. In order that, it will raise the operating cost. Formed propane will be used ass feed for steam methane reforming. This equipment needs natural gas and steam. Propane is used as recovery natural gas feed. The lack of natural gas will be supplied by the other plant. Steam methane reformer is a process in making hydrogen. It will be used for hydro-treating process.