| 梁翠翠,郭洪臣.丁烯催化裂解反应中的C-H键型副反应和化学平衡问题[J].分子催化,2011,(1):69-77 |
| 丁烯催化裂解反应中的C-H键型副反应和化学平衡问题 |
| Catalytic Cracking of Butenes: on the C-H Bond related side-reactions and Chemical Equilibrium |
| 投稿时间：2010-11-08 修订日期：2010-11-29 |
| DOI： |
| 中文关键词: 催化裂解 C-H键反应 醚后碳四液化气 丁烯 纳米ZSM-5沸石 |
| 英文关键词:Catalytic cracking, C-H bond related side-reactions, Post-MTBE C4LPG, Butenes, Nano- sized ZSM-5 zeolite |
| 基金项目:hh |
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| 摘要点击次数: 1558 |
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| 中文摘要: |
| 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。 |
| 英文摘要: |
| The cracking of butenes in post-MTBE C4LPG over modified nano-sized HZSM-5 zeolite catalyst was investigated with small fixed-bed reactor, ammonia temperature-programmed desorption (NH3-TPD) and pyridine-adsorption infrared spectroscopy (Py-IR). Results show that, the propylene selectivity of the butenes catalytic cracking is mainly limited by hydrogen-transfer and dehydrogenation reactions. These C-H bond related side-reactions produce by-products such as alkanes and aromatics, and are responsible for the coking of the catalyst. The decrease of the reaction temperature favors hydrogen-transfer (especially the hydrogen-transfer of isobutene), while the increase of the reaction temperature favors dehydrogenation. On the other hand, dehydrogenation needs strong acid sites, whereas hydrogen-transfer can occur with weak acid sites. As a result, the weakening of catalyst acidity can suppress the C-H bond related side-reactions, and even completely stop dehydrogenation when all the strong acid sites disappear, but it is impossible to avoid hydrogen-transfer under the conditions of butene catalytic cracking. When the catalytic cracking was carried out at 450 ℃ and above, the decrease of butene conversion occurs because of the disproportionation of propylene to butene and ethylene, and the isomerization of normal butenes to isobutene. |
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