A review of catalysts for the gasification of biomass char, with some reference to coal

Abstract

The best catalysts for promoting char gasification are Group I metals, particularly lithium and potassium, although other metals are active to a lesser extent. The most prevalent metal naturally in biomass char is potassium, which is not only inherently active, but volatilises to become finely distributed throughout the char mass. The formation of an active carbon/potassium complex is frequently proposed. Calcium is the other most common active metal found in biomass, but is far less effective and less volatile. In a gasification system the metals remain as carbonate due to the action of carbon dioxide. The alkali metals can react with silica to form silicates, which prevents catalytic action. Transition metals can also participate in catalysis of gasification; iron accelerates gasification and nickel prevents carbon deposition, which helps in conditioning biomass-derived syngas. Volatile iron pentacarbonyl has been identified as a promoter of the char gasification step, with catalytic activity related to the finely dispersed low-valency metal atoms generated during the thermo-decomposition of biomass.

Oil production from mild pyrolysis of low-rank coal in molten salts media

“…Alkali metal species are known to have a good catalytic effect on the pyrolysis and gasification [40][41][42][43][44]. Alkali metal species such as potassium could interact with the carbon and form active carbon/potassium complex which is easier to be decomposed [42].…”

Fast pyrolysis and steam gasification of pellets prepared from olive oil mill residues

“…In literature, gasification process occurs at lower temperatures, but with a catalytic effect (<600 C) [24,25] and also, at higher temperatures (up to 1350 C) than the range of temperatures considered in this study [26e28]. The choice of the present study is based on previous works [10,11,13,23] realized with the same device in the same laboratory (RAPSODEE). Therefore, it is possible to compare the performances of our pellets with wood chips during gasification.…”

“…Investigations on biomass gasification show that syngas composition, depending on the gasification agents, includes H 2 , CO, CO 2 , CH 4 , N 2 , H 2 O and small amounts of tar. The gas concentration depends not only on the used technology and thermodynamic variables, but also on the biomass nature and the gasifier agent [11]. The H 2 and CO are the major interesting gas in the syngas composition since they could be converted to alternative synthetic biofuel through various processes such as Fischer-Tropsch reaction [12].…”

Carbon cycle in advanced coal chemical engineering

“…A carbon cycle for the production of synthetic fuels from biomass and carbon-resources can be seen in Fig. [150][151][152][153][154][155] It was reported that the addition of 10% Scots pine to the coal conversion process can result in a significant 3% reduction in non-renewable carbon emissions and even zero fossil CO 2 emission. Biomass can be directly or indirectly converted into bio-oils, fuels, high value chemicals, food etc.…”