An advanced biomass gasification technology with integrated catalytic hot gas cleaning. Part III: Effects of inorganic species in char on the reforming of tars from wood and agricultural wastes

Abstract

h i g h l i g h t sThe raw and H-form char were used to reform tar in a pilot scale gasifier. The effects of inorganics in the char catalyst on tar reforming were obvious. The catalyst also captured volatilised inorganics from raw gasification gas. a b s t r a c tChar is used directly as a catalyst for the catalytic reforming of tar during gasification. Experiments have been carried out to examine the effects of inorganics in char as a catalyst for the catalytic reforming of tar during the gasification of mallee wood, corn stalk and wheat straw in a pilot plant. The char catalyst was prepared from the pyrolysis of mallee wood at a fast heating rate. The catalytic activities of char and acidwashed char for tar reforming were compared under otherwise identical gasification conditions. For all biomass feedstocks tested for gasification, the tar contents in product gas could be drastically reduced by the catalyst, reaching a tar concentration level well below 100 mg/N m 3 . The acid-washed char also showed profound activity for tar reforming although its catalytic activity was definitely lower than the raw char. Both catalysts could effectively reform the aromatic ring systems (especially large aromatic ring systems with three or more fused benzene rings) in tars as is revealed using UV-fluorescence spectroscopy. The char itself was also partially gasified. After being used as a catalyst, the condensation of the aromatic rings and the accumulation of inorganic species led to drastic changes in char reactivity with O 2 at 400°C. The inorganic species in char tended to enhance the formation of H 2 and CO during the reforming reactions in the catalytic reactor.

Evolution of structure and activity of char-supported iron catalysts prepared for steam reforming of bio-oil

“…Previous studies [11,16] pointed out the char loaded with some catalytically active species showed much higher reactivity for tar reforming than the char itself. The transition metal of iron is believed as an attractive catalytically active species of char-supported catalyst to reform tar during the gasification of biomass by reasons of its high economic feasibility, adequate catalytic activities and non-toxicity [16,17].…”

“…To date, numerous tar elimination techniques, such as thermal cracking, physical capture, catalytic reforming, plasma cracking etc., have been exploited [6,7]. Among these techniques, catalytic tar reforming has been believed widely as a technically and economically feasible method to convert tar into light gas [8][9][10][11][12]. Recently, char/char-supported catalysts, which have the below advantages: (ⅰ) inexpensive and easily available due to the easy and abundant production of char from coal/biomass pyrolysis; (ⅱ) the spent catalyst can be directly/simply gasified/burned to recover the char's energy without any additional regeneration and disposal, have been widely reported as a promising medium to substantially reform/crack tar into light gases and coke [4,11,[13][14][15].…”

Catalytic cracking of ethylbenzene as tar surrogate using pyrolysis chars from wastes

“…This topic has been increasingly investigated over the past few years. Previous studies reported that four characteristics of the chars determined their activity even if their role remains not clear: the porous structures [43,44], the presence of Ocontaining groups on the char surface [45][46][47][48][49], the structure of the carbonaceous matrix [50,51], and the active sites formed by the inherent alkaline (i.e. : Na, K) and alkaline earth (i.e.…”

The influence of preparation method of char supported metallic Ni catalysts on the catalytic performance for reforming of biomass tar

“…De‐SDC10 catalyst reached the maximum syngas yield. The CO and H 2 yields were enhanced, while CO 2 yield decreased from 0.21 to 0.16 mL/g when comparing thermal cracking without catalyst and catalytic cracking with pure char catalyst, which was because of water‐gas shift reaction and the Boudouard reaction between char, H 2 O, and CO 2 in Equations and . In addition, the mass loss of the used SDC catalyst can also verify that char support participated in the reaction at high temperature to produce more CO and H 2 .…”