Biomass derived tar decomposition over coal char bed

Abstract

The effect of coal char on the decomposition of rice straw derived tar was investigated in a two-stage fixed bed reactor. The reactor was divided into a pyrolysis zone (upper part) and a volatile-char contacting zone (lower part). Rice straw was pyrolysed at different temperatures in the upper part. Coal char, prepared by the pyrolysis of Indonesian coal at either 600°C (char600) or 800°C (char800), was located in the lower part. Volatiles from the rice straw (upper part) were produced and then came in contact with the coal char at the lower part under the N 2 (pyrolysis) or steam/N 2 (steam reforming) gas flow. Under pyrolysis, both char600 and char800 exhibited a catalytic effect on the thermal tar decomposition. The coal chars also played a significant catalytic activity on the decomposition of the heavy aromatic hydrocarbons that were generated at a high pyrolysis temperature. In the presence of steam, char600 also exhibited a catalytic role in tar steam reforming, while char800 did not reveal any such significant catalytic activity because of the predominant coke/carbon formation.

Activity of chars and activated carbons for removal and decomposition of tar model compounds – A review

“…This is in agreement with the findings of Hosokai et al [37], who stated that molecules with more fused rings were decomposed faster, and with the preferential adsorption for PAH observed on AC by Mastral et al [17]. Selectivity towards multi-ring aromatics has also been observed by researchers working with thermal decomposition of pyrolysis-derived tars [64,65].…”

Toward Low-Temperature Coal Gasification: Experimental and Numerical Studies of Thermochemical Coal Conversion Considering the Interactions between Volatiles and Char Particles

“…Thus, it is necessary to develop a tar reforming system with high thermal efficiency and without catalyst poisoning or deactivation. The effective decomposition of tar compounds over biomass/coal-derived chars has been frequently reported (Abu El-Rub, 2008;Gilbert et al, 2009;Krerkkaiwan et al, 2015;Krerkkaiwan et al, 2013;Sun et al, 2011). Naphthalene, representative of the most refractory compounds among tar constituents, was decomposed almost completely over chars or charcoals from different biomass/coals within a short gas residence time (less than 0.25 s) in a fixed-bed reactor (Abu El-Rub et al, 2004b;Fuentes-Cano et al, 2013).…”

Catalytic effect of rice straw‐derived chars on the decomposition of naphthalene: The influence of steam activation and solvent treatment during char preparation

“…Carbon‐based catalysts, such as pyrolysis char, activated carbon, and gasified char, are attractive catalysts for the tar removal process, due to their effectiveness and relatively low cost. Many researchers have identified the catalytic performance of carbon‐based catalysts, such as coal char and wood char, as well as the co‐pyrolysis char, in terms of the increased gas production and tar conversion. El‐Rub et al reported that biochar made from pine wood pyrolysis was the most effective catalyst for naphthalene conversion at 900°C, among the other low cost catalysts (dolomite, olivine, and spent fluid catalytic cracking catalyst [FCC]).…”

“…In addition, the lifetime of the biochar was longer. Coal char and co‐pyrolysis char were also used for tar steam reforming to decrease tar yield and increase gas products, especially H 2 and CO production . There are two main aspects related to the catalytic performance of the carbon‐based catalysts.…”

“…The coal char prepared at 600°C had a higher BET surface area and pore volume than the char prepared at 800°C and could act as the better catalyst for tar reduction to enhance the gas production . Zhang et al also reported that rice straw char (RSC) prepared at high temperatures (>600°C) and long residence times would greatly reduce the number of micropores on the char, resulting in a faster deactivation of the char during tar cracking.…”