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用小型固定床反应器以及氨气程序升温脱附(NH3-TPD)和吡啶吸附红外光谱(Py-IR)研究了醚后碳四液化气中的丁烯在改性纳米ZSM-5沸石催化剂上的催化裂解反应.结果表明,丁烯催化裂解反应的丙烯选择性主要受氢转移和脱氢反应制约.这些C—H键型反应生成烷烃和芳烃副产物,并导致催化剂积炭.低温有利于氢转移(尤其异丁烯的氢转移反应),高温有利于脱氢.脱氢反应需要强酸中心,但氢转移反应在弱酸中心上也能进行.因此,通过改性降低催化剂的酸度虽然可以有效抑制C—H键型副反应,甚至消除脱氢副反应,却不能完全阻止氢转移副反应.在450℃以上的高温下,产物丙烯生成丁烯和乙烯的歧化反应,以及正丁烯向异丁烯的异构化反应导致了丁烯转化率的降低.
A small fixed-bed reactor was used to study the effect of butene on the modified nano-ZSM-5 zeolite catalyst after NH3-TPD and Py-IR. .The results showed that the propylene selectivity of butene was mainly controlled by hydrogen transfer and dehydrogenation reactions.These C-H bond-type reactions produced by-products of alkanes and aromatics and led to the catalyst carbon deposition.The low temperature was favorable Hydrogen transfer (especially the isobutene hydrogen transfer reaction), high temperature is conducive to dehydrogenation dehydrogenation reaction requires a strong acid center, but the hydrogen transfer reaction can also be carried out in the weak acid center .Through the modification to reduce the acidity of the catalyst although it can effectively inhibit the C -H bond side reactions, and even eliminate the side reaction of dehydrogenation, but can not completely prevent the side reaction of hydrogen transfer.At 450 ℃ above the high temperature, the propylene propene produces butylene and ethylene disproportionation reaction, as well as the difference of n-butene to isobutene The structuring reaction leads to a decrease in butene conversion.