在Zn-Cr催化剂上超临界相合成低碳醇的链增长机理

A CHAIN GROWTH SCHEME FOR HIGHER ALCOHOLS SYNTHESIS OVER Zn-Cr CATALYST IN SUPERCRITICAL FLUIDS

在固定床反应器中 ,用化学富集法研究了在Zn -Cr催化剂上超临界相合成低碳醇的链增长机理 ,得到超临界流体中低碳醇形成的链增长模式和产物分布方程 ,分析了超临界流体对低碳醇形成链增长的影响。结果表明 ,低碳醇的形成是以碳链增长的方式进行的 ,COH α CCOH β CCCOH β CC(CH3)COH为低碳醇形成的机理。在链增长各步骤中 ,α -加成速度慢 ,是低碳醇形成的控制步骤 ,β -加成速度快 ,为链的增长步骤。超临界流体的引入改变了链增长各步的相对速度 ,其中链增长控制步骤和生成异丁醇的终止步骤的速度被加快 ,从而得到了超临界相合成的高C+2 OH和高异丁醇含量的有利产物分布。

The mechanism of carbon chain growth for higher alcohol synthesis from syngas over Zn-Cr catalyst in supercritical fluids was studied by chemical enrichment in a fixed-bed reactor The carbon chain growth scheme and product distribution equations were obtained The effect of supercritical fluids on the higher alcohols synthesis was also discussed Results indicated that the formation of higher alcohols took place in a sequential manner and the formation mechanism of higher alcohols was COH α CCOH β CCCOH β CC(CH3)COH α-addition was a slow initial step while β-addition was a faster one, the former being the rate-determining step and the latter being the carbon chain growth step among the steps of carbon chain growth The rates of α-addition and β-addition producing isobutanol were enhanced by the introduction of supercritical fluid, resulting in high C+2OH and isobutanol contents in supercritical synthesis