Catalytic fast pyrolysis of eucalyptus wood was performed on a continuous laboratory-scale fluidized bed fast pyrolysis system. Catalytic activity was monitored from use of fresh catalyst up to a cumulative biomass/catalyst ratio (B/C) of 4:1 over extruded pellets of three different ZSM-5 catalysts by tracking CO, CO₂, H₂, and C₂H₄ production and bio-oil quality. The catalysts employed were extruded HZSM-5 with two different silica/alumina ratios (30 and 80) as well as one modified with Ga (SiO₂/Al₂O₃ = 30) by ion exchange, which was reduced under H₂ prior to pyrolysis. The deactivation of the catalysts over the course of the experiment was reflected in the decline in deoxygenation activity, following the order HZSM-5 (30) > HZSM-5 (80) > GaZSM-5 (30). HZSM-5 (30) lost most of its activity before a cumulative B/C of 2:1 was reached, while HZSM-5 (80) still showed significant deoxygenated activity at this exposure level. GaZSM-5 (30) still showed deoxygenation activity at B/C of >4:1. The improvement exhibited by HZSM-5 with an increasing SiO₂/Al₂O₃ ratio was attributed to reduced acid site density that decreased the propensity for coke formation as a result of reactions occurring between substrates at adjacent active acid sites. For reduced GaZSM-5, initial dehydrogenation activity aided in the production of aromatics by the olefin oligomerization and aromatization route up to B/C of ∼1.5:1, after which Ga became completely oxidized; however, the oxidized GaZSM-5 catalyst continued to exhibit improved decarbonylation and decarboxylation activities.

中文翻译：

---

HZSM-5对桉树的流化床催化热解：酸密度和镓改性对催化剂失活的影响

在连续实验室规模的流化床快速热解系统上进行桉木的催化快速热解。通过跟踪CO，CO ₂，H ₂和C ₂ H ，从使用新鲜催化剂到与三种不同ZSM-5催化剂的挤出颗粒相比，累积的生物质/催化剂之比（B / C）达到4：1来监测催化活性。₄生产与生物油质量有关。使用的催化剂是通过两种不同的二氧化硅/氧化铝比率（30和80）以及一种通过离子交换用Ga改性的HZSM-5（SiO ₂ / Al ₂ O ₃ = 30）在H ₂下还原而挤出的。热解之前。在整个实验过程中，催化剂的失活表现为脱氧活性的下降，依次为HZSM-5（30）> HZSM-5（80）> GaZSM-5（30）。在累积B / C达到2：1之前，HZSM-5（30）失去了大部分活性，而HZSM-5（80）在此暴露水平下仍显示出明显的脱氧活性。GaZSM-5（30）在B / C> 4：1时仍显示出脱氧活性。HZSM-5随着SiO ₂ / Al ₂ O ₃的增加而表现出的改进该比率归因于降低的酸位点密度，这降低了由于相邻活性酸位点之间的底物之间发生反应而导致焦炭形成的倾向。对于还原的GaZSM-5，最初的脱氢活性有助于通过烯烃低聚和芳构化途径直至B / C约为1.5：1来生产芳烃，此后Ga完全被氧化。然而，氧化的GaZSM-5催化剂继续表现出改善的脱羰和脱羧活性。