Direct synthesis of middle iso-paraffins from synthesis gas
Direct synthesis of middle iso-paraffins from synthesis gas
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DOI：
10.1016/s0920-5861(03)00301-8
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发表时间：
2003-08
期刊：
影响因子：
5.3
通讯作者：
Xiaohong Li;K. Asami;M. Luo;Keisuke Michiki;N. Tsubaki;K. Fujimoto
中科院分区：
文献类型：
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作者：
Xiaohong Li;K. Asami;M. Luo;Keisuke Michiki;N. Tsubaki;K. Fujimoto
研究了Co/SiO2催化剂上费托合成富异构烷烃的反应。基本概念是将初级FTS烃产物二次异构化和/或加氢裂化。在Co/SiO2催化剂中加入少量H-ZSM-5的物理混合物促进了C4-C10异构烷烃的生成，同时抑制了长链烃的生成，这可能是由于ZSM-5对高级烃的选择性裂解。三组分催化剂（Co/SiO2-Pd/SiO2-ZSM-5）促进了烷烃的生成，但异构化产物收率不高。对于两步反应，第一步催化剂是Co/SiO2+ZSM-5催化剂，第二步催化剂是Pd/SiO2+ZMS-5催化剂，其中加入额外的氢气。在保持合成气转化率不变的情况下，异构烷烃的选择性显著提高，产物分子量降低。正辛烷（FTS反应的模型化合物）在Pd/SiO_2-沸石复合催化剂上加氢裂化，表现出较高的活性和稳定性，生成富含异构烷烃的烃类。富钯催化剂有利于异构化反应。Pd的作用被认为是氢溢流到沸石上的孔道。
This paper focuses on the synthesis of iso-paraffin-rich hydrocarbons by Fischer–Tropsch synthesis (FTS) over Co/SiO2catalyst. The basic concept was to secondarily isomerize and/or hydrocrack the primary FTS hydrocarbon products. A physical mixture of a small amount of added H-ZSM-5 in the Co/SiO2catalyst enhanced the formation of C4–C10iso-paraffins while suppressing the formation of longer hydrocarbons, probably because of the selective cracking of higher hydrocarbons on ZSM-5. The three-component catalyst (Co/SiO2–Pd/SiO2–ZSM-5) promoted the formation of paraffins, whereas the yield of isomerized products was not high enough. For a two-step reaction, the first step catalyst was the Co/SiO2+ZSM-5 catalyst and the second step catalyst was Pd/SiO2+ZMS-5 catalyst where additional hydrogen was added. The selectivity of iso-paraffins was markedly promoted and the molecular weight of the product decreased while the syngas conversion was kept constant. The hydrocracking of n-octane (which is the model compound of FTS reaction) over hybrid catalyst composed of Pd/SiO2–zeolite and showed high and stable activity giving iso-paraffin-rich hydrocarbons. The isomerization was favored for Pd rich catalyst. The role of Pd was thought to be the port hole of hydrogen spillover to zeolite.