Catalytic activities of nickel, dolomite, and olivine for tar removal and H₂-enriched gas production in biomass gasification process

Abstract

Tar content in gasification products is a serious problem for fuel gas utilization in downstream applications. Catalytic steam reforming of tar to syngas is a promising way for the removal of tar from the gas products. Nickel-based catalysts, dolomite, and olivine have been widely investigated for tar cracking and reforming by various researchers. This paper presents a review of biomass gasification, tar composition, and its elimination process by using the above three catalysts. This paper summarizes the knowledge in the published literature associated with tar elimination during the biomass gasification including discussion on the effects of different support, promoter on the catalytic performance. The aim of this paper is to collect information on the performance of above catalysts to make them accessible to readers within one paper. Comparative studies on these catalysts carried out by some researchers have also been presented here which show that the nickel-based catalyst is much more active than dolomite and olivine, but they are more expensive and can be also deactivated. Compared to olivine, the dolomite shows better catalytic performance with much higher gas yield and H2. Calcination of these catalysts improves the catalytic activities but the amount of coke deposited on the surface of the dolomite is reported higher than that of the olivine, which may be resulted from the different Fe amount of the catalyst.

Catalytic steam‐gasification of biomass in a fluidized bed reactor

“…The gas yield was increased, while the tar and char yield showed an opposite trend with the temperature due to the endothermic nature of the reactions involved. As can be seen, tar cracking and char conversion increased slowly at lower temperatures (750–800 °C) and rapidly at higher temperatures (800–900 °C), which may be due to the enhanced tar cracking and char oxidation reactions at higher temperatures . At 900 °C, a tar yield of 0.5% and 4.3% and a char yield of 2.4% and 3.2% were obtained for steam gasification of birch wood using calcined dolomite and calcined olivine, respectively.…”

“…Swierczynski et al 10 developed a Ni/olivine catalyst for tar destruction during fluidized bed gasification of biomass and concluded that an olivine-supported Ni catalyst causes a higher toluene conversion and a low carbon formation compared with untreated olivine. Soomro et al 11 compared catalytic activity of olivine, dolomite and nickel for tar craking, and showed that the catalytic activity of Ni-based catalysts is better than that of dolomite and olivine but they are more expensive. Yang et al 12 developed a Ni/olivine (Ni/MO) catalyst for tar decomposition in biomass gasification.…”

Synthetic fayalite Fe2SiO4 by kinetically controlled reaction between hematite and silicon carbide

“…Different catalysts have been proposed to promote the elimination of tars, including their catalytic reforming, with emphasis on catalysts based on Ni (Ni/Al 2 O 3 , Ni/MgAl 2 O 4 ,…) and low‐cost natural minerals such as dolomite, CaMg(CO 3 ) 2 , and olivines, (Fe,Mg) 2 SiO 4 . Nickel‐based catalyst are much more active than dolomite and olivine, but also are more expensive and are easily deactivated due to coking and sulfur poisoning . Olivine may show similar catalytic activity for the tar removal compared to dolomite but is advantageous in terms of better attrition resistance and better resistance to carbon deposition .…”

“…[11][12][13][14][15][16][17][18] Nickel-based catalyst are much more active than dolomite and olivine, but also are more expensive and are easily deactivated due to coking and sulfur poisoning. 11,12,19 Olivine may show similar catalytic activity for the tar removal compared to dolomite 20,21 but is advantageous in terms of better attrition resistance and better resistance to carbon deposition. 13,19 However, the mechanisms of catalytic activity of olivines and corresponding influencing factors (compositional effects, thermal pretreatments and their structural and microstructural effects) are still poorly understood, 13,16,22 possibly because the exact composition and other characteristics of natural minerals are ill defined.…”

“…11,12,19 Olivine may show similar catalytic activity for the tar removal compared to dolomite 20,21 but is advantageous in terms of better attrition resistance and better resistance to carbon deposition. 13,19 However, the mechanisms of catalytic activity of olivines and corresponding influencing factors (compositional effects, thermal pretreatments and their structural and microstructural effects) are still poorly understood, 13,16,22 possibly because the exact composition and other characteristics of natural minerals are ill defined. Thus, synthetic Fe 2 SiO 4 may be expected to provide the best conditions for detailed catalytic studies.…”