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Char is a low-value byproduct of biomass gasification and pyrolysis with many potential applications, such as soil amendment and the synthesis of activated carbon and carbon-based catalysts. Considering these high-value applications, char could provide economic benefits to a biorefinery utilizing gasification or pyrolysis technologies. However, the properties of char depend heavily on biomass feedstock, gasifier design and operating conditions. This paper reports the effects of biomass type (switchgrass, sorghum straw and red cedar) and equivalence ratio (0.20, 0.25 and 0.28), i.e., the ratio of air supply relative to the air that is required for stoichiometric combustion of biomass, on the physiochemical properties of char derived from gasification. Results show that the Brunauer-Emmett-Teller (BET) surface areas of most of the char were 1-10 m 2 /g and increased as the equivalence ratio increased. Char moisture and fixed carbon contents decreased while ash content increased as equivalence ratio increased. The corresponding Fourier Transform Infrared spectra showed that the surface functional groups of char differed between biomass types but remained similar with change in equivalence ratio. OPEN ACCESSEnergies 2013, 6 3973

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The activated carbons (ACs) enriched in P-containing functional groups were obtained through one-pot microwave-induced pyrolysis from corn stover activated with phosphoric acid and were further tested as the catalyst for selective monophenol production from cellulose pyrolysis for the first time. Maximum AC yield (44.3 wt %) was obtained with an acid to biomass ratio of 0.85. Increasing phosphoric acid to corn stover ratios could enhance the porosity and peak intensities of Pcontaining functional groups in obtained ACs. Attained ACs had an excellent catalytic performance in phenol production with the highest selectivity of phenol (99.02 % based on peak area) in the obtained organic compounds at the catalytic temperature of 450 °C. The catalytic performance of ACs remained highly selective for phenol after using two times. The experimental results indicated that P-containing groups such as −O−P, OP, and −O−P−O− were the active reaction sites and more mespores promoted phenol production. The phenol can be generated from reforming of levoglucosenone and furfural over AC catalysts. The present work provides an efficient route to produce high selective monophenol from cellulose pyrolysis by using activated carbons as the catalyst, which further advanced the utilization of biomass to produce high-value chemicals.

The purpose of this study was to utilize gasification derived char as a catalyst support for tar removal. Red cedar char collected from downdraft bed gasification was chemically activated into activated carbon and impregnated with nickel acetate and nickel nitrate. The effects of nickel salts precursor, nitric acid treatment of support and reduction of nickel in hydrazine medium on catalyst performance were studied. It was found nickel nitrate was a better nickel precursor than nickel acetate for preparation of char supported nickel catalyst. The catalyst impregnated with nickel nitrate was found more active in steam reforming of toluene than catalyst impregnated with nickel acetate. The TEM results indicated that the nickel particle size of catalyst impregnated with nickel nitrate was much smaller than that of catalyst impregnated with nickel acetate. Toluene showed higher removal efficiency than naphthalene. The presence of naphthalene decreased the toluene removal.

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