Fischer‐Tropsch Catalysts for the Biomass‐to‐Liquid (BTL)‐Process

Abstract

The Fischer-Tropsch synthesis is at the heart of the Biomass-to-Liquids (BTL) process. Feasibility studies published in open literature typically consider cobaltbased catalysts for the Fischer-Tropsch synthesis. Here, we present an overview on the history and development up until the present for both cobalt-and ironbased Fischer-Tropsch catalysts. The role of the support material and various other additives to the catalyst formulation are discussed in detail with regard to activity, catalyst deactivation, and selectivity. Tentative explanations for e.g. the observed size dependency in cobalt-based catalysts and phase transformations in iron-based Fischer-Tropsch catalysts are offered. The productivity of cobalt-based catalysts at high conversion level is currently higher than that of iron-based catalysts. Nevertheless, it is argued that iron-based catalysts may be an attractive option for the BTL-process, since it is much cheaper, impacting on the cost of the process due to inevitable process set-ups in industrial operation. Improvement of current iron-based catalysts is however desired.

A review of Fischer Tropsch synthesis process, mechanism, surface chemistry and catalyst formulation

“…Cobalt, iron, ruthenium and nickel are considered as commercial catalysts in bio-fuel generation. These metals in their metallic form have the capability like all elements of VIII B group in the periodic table [52] to dissociatively adsorb carbon monoxide to form metal carbide on the catalytic surface and hydrogenate the adsorbed carbides. Ruthenium is not of interest for commercial application because of its high cost; despite the fact that it is one of the most active catalysts for F-T synthesis.…”

“…The low average molecular weight of nickel prevents the usage of this metal for the F-T process. The small particle size of nickel leads to higher hydrogenation activity power compared to its chain growth power [52] Water Gas Shift (WGS) reaction activity over an iron catalyst in the F-T process is more than that of cobalt, which can lead to loss of carbon monoxide as a raw material by the formation of carbon dioxide. The activity of the WGS reaction produces more water as a co-product of this process, which is the kinetic inhibition of an iron catalyst.…”

Recent Progresses in Understanding of Co-Based Fischer–Tropsch Catalysis by Means of Transient Kinetic Studies and Theoretical Analysis

“…Fischer-Tropsch synthesis (FTS) is an alternative process for producing transportation fuels and chemicals by converting syngas derived from natural gas, biomass and coal [1][2][3][4]. Recently, the increase in demand for transportation fuels and the large reserves of natural gas have made FTS an attractive industrial process.…”

“…Besides, it is possible that the reaction mechanism may change with different reaction conditions and catalysts. There are several excellent reviews regarding the FTS mechanism [1,2,[18][19][20][21]. The reaction mechanism for such a complex reaction is still a project of controversy and uncertainty despite the fact that it has been explored by many experimental and theoretical studies.…”

The role of Cu on the reduction behavior and surface properties of Fe-based Fischer–Tropsch catalysts

“…The Fe-based FTS catalysts also catalyze the water-gas shift reaction (WGS) under typical reaction conditions and therefore these materials are of prime interest for the conversion of hydrogen lean (CO/H 2 E 1) synthesis gas types, like those derived from coal and biomass. 5 Both carbon sources are expected to play a large role in future FTS applications.…”