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Chapter 5: The Influence of Reaction Conditions on Catalytic Reforming 1. Reaction Temperature: From the perspective of chemical equilibrium, the main reactions in catalytic reforming, such as the dehydrogenation of hexacyclic alkanes and the dehydrogenative cyclization of alkanes, are all endothermic reactions. Therefore, from the perspective of chemical equilibrium, it is desirable to use a higher reaction temperature. Weighted average bed temperature (or weighted mean bed temperature): it is the average temperature calculated by taking into account the amount of catalyst at different temperatures. The definition formula for the weighted average bed temperature Tm is: 2. Reaction pressure: From a chemical equilibrium perspective, increasing the pressure is unfavorable for the dehydration of hexacyclic alkanes to form aromatics as well as for the cyclization of alkanes through dehydration; instead, it favors the side reactions of hydrocracking. Therefore, using a lower pressure is beneficial for obtaining higher yields of liquid products and aromatics. From a kinetic perspective: when using a single platinum catalyst, the reaction pressure is generally around 3 MPa ； When a platinum-rhodium catalyst is used, its high carbon capacity allows the reaction pressure to be reduced to around 1.5 MPa ； When a platinum-tin catalyst is used, the amount of carbon deposition is lower under the same conditions compared to that with a platinum-rhodium catalyst, allowing the pressure to be further reduced below 1 MPa. Currently, the reaction pressure for continuous regenerated catalytic reforming can be reduced to as low as 0.4 MPa. 3 In space velocity catalytic reforming, the reaction rates of various reactions differ considerably. For the hexacyclic alkane dehydrogenation reaction, which has a high reaction rate, the effect of space velocity is minimal; whereas for the alkane dehydrogenation cyclization reaction, which has a lower reaction rate, the effect of space velocity is more significant. Therefore, a higher space velocity can be used for naphthenic and intermediate-chain feedstocks, while a lower space velocity is required for paraffinic feedstocks. For the same feedstock, increasing the space velocity raises the liquid yield, but at the same time it reduces the reforming conversion rate, resulting in a lower octane number. The space velocity used in reforming units equipped with platinum-rhodium catalysts is generally 1.0–2.0 h-1. If the space velocity is below 1.0 h-1, the increase in side reactions such as hydrocracking leads to a lower yield of liquids. 4 Hydrogen-to-oil ratio: In the catalytic reforming process, the hydrogen-to-oil ratio refers to the molar ratio of hydrogen in the recycle gas to that in the reaction feed. However, the hydrogen-to-oil ratio cannot be too high either; an excessively high ratio is unfavorable for reactions that produce hydrogen gas, such as the dehydrogenation of hexacyclic naphthenes and the dehydrogenative cyclization of alkanes. Meanwhile, the greater the amount of hydrogen circulated, the more energy is consumed. Currently, the hydrogen-to-oil ratio in catalytic reforming units is generally between 3.5 and 7; for continuously regenerated reforming, this ratio can even be reduced to 2.