Fischer-Tropsch process for converting synthesis gas to a lower olefin

摘要

Effect Fischer-Tropsch synthesis of lower olefins by converting a syngas feedstream at a temperature within a range of from 300° C. to no more than 400° C. using a supported, iron-based catalyst under a total system pressure of at least 2 megapascals with a volumetric ratio of hydrogen to carbon monoxide of at least 3:1 with markedly lower coking rates than attainable at a total system pressure of less than 2 megapascals.

主权项

1. An improved Fischer-Tropsch process for producing lower olefins by conversion of a feed stream comprising carbon monoxide and hydrogen at a temperature within a range of from greater than 300° C. to no more than 400° C. using a supported, iron-based catalyst that consists essentially of iron-containing particles dispersed onto a support that is chemically inert toward iron, with a loading of such particles of at least 1 weight percent based upon total catalyst weight, wherein the improvement comprises selecting as the support an alpha alumina, and effecting the conversion at a combination of a) a total system pressure of at least 20 Bars (2 megapascals), b) a volumetric ratio of hydrogen to carbon monoxide of at least 3:1, and c) a hydrogen partial pressure of at least 15 Bar (1.5 megapascals), whereby conversion at the combination leads to substantially lower levels of coking on the catalyst than one encounters with the same catalyst, but with Fischer-Tropsch process parameters that differ from the combination, the substantially lower levels of coking on the catalyst being a coke formation rate after four hours time on stream of less than 1×10−7 moles of carbon per gram of catalyst per second.