Effect of Heating Rate on Steam Gasification of Biomass. 2. Thermogravimetric-Mass Spectrometric (TG-MS) Analysis of Gas Evolution

Abstract

Evolution rates of low-molecular-weight gas products (H 2 , CH 4 , CO, and CO 2 ) in pyrolysis and steam gasification of biomass (cellulose and lignin) were studied using thermogravimetric-mass spectrometric (TG-MS) analysis. Total gas yields were measured with a TCD-micro gas chromatograph (micro GC) at heating rates of 1, 10, and 100 K s -1 . Steam gasification of biomass demonstrated heating rate effects on gas evolution: 81 wt % of cellulose was converted into tar in pyrolysis; also, slow heating and steam gasification of nascent char occurred above 700 K, evolving H 2 . Rapid heating significantly enhanced secondary pyrolysis of cellulose tar to yield H 2 , CO, and CH 4 . In contrast, char formation at 500-773 K was dominant in lignin pyrolysis. Evolution of H 2 and CO 2 were significantly increased by steam gasification of char. Insignificant influence of heating rate on carbon and hydrogen yield of lignin was observed. Over 70% of lignin's chemical energy was converted into gas, especially hydrogen.

A simple kinetic analysis of syngas during steam hydrogasification of biomass using a novel inverted batch reactor with instant high pressure feeding

“…When the heating rate was slow, the char yield was above 35% and the syngas yield was about 10% lower than that of fast heating rate by instant feedstock loading. In addition, the heating rate could have direct impact on reaction kinetics and higher heating rate could lead to lower activation energy (Fushimi and Araki, 2003). When there was no agitation in the reactor at 700 °C, higher char yield and lower syngas yield can be observed, indicating the impeller played a very important role in enhancing the gas-solid reaction.…”

Impact of Biochar on Organic Contaminants in Soil: A Tool for Mitigating Risk?

“…The final thermal conversion of wood yields three basic products; liquid (liquid hydrocarbon and water), solid (biochar) and gas [81]. Wood feedstock, containing higher lignin content, produce the highest biochar yields at 500 °C compared to lower and higher temperatures of pyrolysis [82]; Table 1 highlights the fate of feedstock in a thermal treatment reactor. The physicochemical properties of the biochar largely depend on the heating temperature.…”

The Influence of Feedstock Type and Operating Parameters on Tar Formation in the Process of Gasification and Co-Gasification

“…After 120 s of the residence time the primary products from cellulose were almost entirely decomposed, while the lignin-derived primary tars were transformed into the secondary tars. Fushimi et al [35] proved that the steam gasification of the lignin-derived chars was effective only at the temperature over 650ºC. Hanaoka et al [36] emphasized relatively low reactivity of lignin in the process of gasification with air and steam, even at 900ºC.…”