Duo Wang

USE OF BIOMASS HYDROTHERMAL CONVERSION CHAR AS THE NI CATALYST SUPPORT IN BENZENE AND GASIFICATION TAR REMOVAL

One of the major issues in biomass gasification is removal of tars from syngas. Catalytic reforming of tars is considered the most promising in large-scale applications because of its fast reaction rate and reliability. In this study, a new Ni/char catalyst was prepared and used for woodchip gasification tar removal and reforming in a downdraft gasifier Benzene was used as the model tar to optimize catalytic reaction conditions. Three parameters were investigated: reaction temperature (700 °C to 900 °C), gas residence time (0.1 to 1.2 s), and catalyst loadings (5% to 20% weight of char support). On the basis of the benzene test, a reaction temperature of 800 °C, catalyst loading of 1 wt%, and residence time of 0.3 s were chosen as optimum reaction conditions. Testing these parameters in a downdraft biomass gasifier showed that the Ni/char catalyst removed more than 99% of tars and significantly increased the concentrations of combustible compounds in the syngas. From their initial levels before the catalytic reforming to their final levels after the catalytic reforming, H 2 and CO in the syngas increased from 20.43% to 51.90% and from 14.20% to 18.36 % , respectively. Performance of the new catalyst in terms of tar removal rate and syngas reforming was similar to that of Ni/γ-Al 2 O 3 catalysts.

Catalytic oxidation of lignin–acetoderivatives: a potential new recovery route for value-added aromatic aldehydes from acetoderivatives

Catalytic wet air oxidation (CWAO) of lignin and phenolic composition of wastewater is a useful pathway towards the recovery of valuable compounds. In this study, bamboo lignin was catalytically oxidized to aromatic aldehydes and acetoderivatives; similarly acetovanillone and acetosyringone were oxidized to vanillin and syringaldehyde, respectively. A total product yield of 9.5% from bamboo lignin and a vanillin yield of 51% with greater than 90% selectivity from acetovanillone were achieved. The proposed reaction pathways suggest a two-step route towards the formation of value-added aromatic aldehydes from lignin via degradation of acetoderivatives. The kinetics study for the degradation of acetovanillone and formation of vanillin was reported for the first time in the temperature range of 120–150 °C, with activation energies of 85.29 kJ mol−1 and 120.7 kJ mol−1, respectively. To date, CWAO breaks down the lignin polymer and toxic phenolic compounds reasonably and effectively, producing value-added aldehydes, which could become a potential new route for the recovery of value-added products.

The development of a real-time thermogravimetric analyzer on the gasification of pine sawdust in a simulated fluidized bed gasifier

ABSTRACT In this study, a real-time thermogravimetric analyzer was developed for providing insight into the reactivity and gasification process of pine sawdust. The mass loss rate of pine sawdust, syngas composition, and tar compounds in the gasification process were analyzed at different gasification conditions. According to the real-time thermogravimetric analysis, 800°C of the gasification temperature, 0.25 of the equivalence ratio, and 600 kg/(m2·h) of the gasification throughput were regarded as an optimum conditions for the gasification of pine sawdust in a fluidized bed gasifier.