Development of nickel‐activated catalytic filters for tar removal in H₂S‐containing biomass gasification gas

Abstract

The urea method was applied to deposit a nickel-calcium catalyst inside porous filter discs to develop a gas cleaning technique involving the combined removal of tars and particles from hot biomass gasification gas. Some catalytic filter discs were tested in typical filtration conditions for the decomposition of the model tar compound benzene in a simulated biomass gasification gas containing representative amounts of H 2 S. H 2 S-deactivation studies showed a significant improvement in the sulfur resistance of the nickel catalyst on the filter discs by the addition of CaO to the catalyst formulation. The optimisation of the ratio between Ni and CaO and the effect of nickel content in the catalyst formulation on the catalytic performance were investigated.

Recent progress in gasification/pyrolysis technologies for biomass conversion to energy

“…Considerable efforts have been directed toward tar removal from fuel gas in the biomass gasification process. Some of the approaches include physical processes such as filters [21] or wet scrubbers [22], and thermal processes of high temperature cracking [23] and catalytic cracking [24,25]. Catalytic cracking is recognized as the most effective method to reduce the tar formation.…”

Conversion of Biomass on Solid Catalysts

“…The pilot plant is a bubbling fluidized bed with steam-oxygen mixtures, with a calcined dolomite guard bed being used to reduce the initial level of tars from the gasifier. As hot filters are necessary with powder catalysts, it was proposed that nickel catalysts should be loaded into ceramic candle filters in order to combine efficient particle removal with tar reforming [334][335][336]. The tar conversion over the monolith varied from 21% to 96%, depending on the operating conditions [310].…”

Atomic Layer Deposition Coated Filters in Catalytic Filtration of Gasification Gas

“…Cost savings of 5% can be achieved by performing the filtration at a higher temperature of over 800 • C, since the previous and following unit operations-gasification and reforming, respectivelyare performed at the higher temperature as well [8]. By adding catalytic functionality to the filter, the reforming of tar and methane can also be performed during filtration to increase the process performance or completely eliminate the need for a separate reforming unit [10,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. A lifetime of at least 1-2 years is required for reforming the catalyst used in hydrogen or methane production from biomass in order to be economically feasible [8].…”

“…The challenge in the preparation of the catalytically coated filters is the low surface area, in the order of 0.3 m 2 /g, of the filter media. This acts as a catalyst support, and thus limits the surface area of the active metal and therefore causes low activity, especially in the presence of sulfur compounds [21,25]. The deposition of a highly dispersed support layer has been proposed to increase the surface area of the filter media, thus allowing a higher loading of active metal [21,25].…”

“…This acts as a catalyst support, and thus limits the surface area of the active metal and therefore causes low activity, especially in the presence of sulfur compounds [21,25]. The deposition of a highly dispersed support layer has been proposed to increase the surface area of the filter media, thus allowing a higher loading of active metal [21,25]. Zhao et al [26] compared different deposition methods for the nickel in α-Al 2 O 3 filter substrates, and found that deposition-precipitation with urea provides more uniform coatings.…”