Catalytic Steam Reforming of Biomass-Derived Tar over the Coal/Biomass Blended Char: Effect of Devolatilization Temperature and Biomass Type

Abstract

Catalytic tar steam reforming over char was conducted in a two-stage fixed-bed reactor. This reactor was divided into two zones: the "devolatilization zone", where the biomass tar is released, and the "tar reforming zone", where the tar and char are contacted and reformed into products. The temperature of the tar reforming zone was maintained at 800 °C for all experiments. The effects of devolatilization temperature (600, 700, and 800 °C) and biomass type (rice straw, RS, and Leucaena leucocephala wood, LN) on the catalytic performance of char during tar steam reforming were investigated. Biomass chars and coal/biomass blended chars (C/RS and C/LN) were prepared as the catalyst for tar steam reforming. Results revealed that compared with biomass chars, C/RS and C/LN performed a better catalytic activity in tar steam reforming, resulting in a higher carbon conversion into gas and a lower carbon conversion into tar. The main catalytic roles of the coal/biomass blended char can be explained by the improvement of the Brunauer−Emmett−Teller (BET) surface area during co-pyrolysis and the existence of alkali and alkaline earth metallic species (AAEMs), particularly K, as the stable silicate form. Considering the effect of devolatilization temperature, the tar released at 700 °C can be mostly converted among all types of char. Tars containing the mixture of phenolic compounds (i.e., phenol and methyl phenol) and aromatic compounds (i.e., naphthalene and methyl naphthalene) were favorable to reform over the char surface to achieve the relatively high tar conversion. In addition, LN tar was easier to convert than the RS tar in both cases of with and without char because of the lower proportion of a stable aromatic compound. The outcome of this study can be beneficial for the design and operation of the tar removal process during biomass gasification using the low-cost carbon-based catalyst.

Cobalt Carbide from Co–Mn Layered Double Hydroxide: Highly Efficient Catalyst for Toluene Pyrolysis

“…In a thermochemical process (gasification or pyrolysis) of biomass, the cracking of tar into other noncondensable gaseous species, especially hydrogen, is still a technical barrier to overcome. , Usually, for catalytic cracking of tar toward producing more hydrogen, a model molecule such as toluene was widely investigated based on technologies such as steam reforming, which however is hard to control. , Thermal catalysis of toluene is a simple method, for which Ni-based catalysts are usually used because of their high activation ability of C–H and C–C bonds; − for example, Ni/γ-Al 2 O 3 can reach a toluene conversion rate of 85.9% at 750 °C, mainly producing hydrogen (over 90%) and other hydrocarbons (CH 4 , C 2 H 4 , C 2 H 6 , and C 2 H 2 ) . Even though its catalytic performance can be tuned by altering loading amounts of Ni and types of additives (Fe, Mg, Mn, and Ce), coking and sintering are still crucial problems. , …”

Síntese de materiais carbonáceos a partir de palha de café arábica para remoção de contaminantes em sistemas aquosos

“…A utilização do biochar como suporte de diferentes catalisadores para o craqueamento do alcatrão pode ser implementada, simultaneamente, dentro do carbonizador [71]. Vários catalisadores vêm sendo investigados para alcançar uma alta conversão de bio-óleo [68].…”