Upgrading biomass fuel gas by reforming over Ni–MgO/γ-Al 2O 3 cordierite monolithic catalysts in the lab-scale reactor and pilot-scale multi-tube reformer

Abstract

The effect of Ni/Mg mole ratio of Ni–MgO/γ-Al 2O 3 cordierite monolithic catalysts on dry reforming of model biomass fuel gas(H 2/CO/C 2H 4/CH 4/CO 2/N 2 = 16.0/12.1/2.5/15.1/22.0/32.3, vol.%) was investigated in a lab-scale stainless steel tubular reactor. The results showed that CH 4 and CO 2 conversions, H 2 and CO yields and H 2/CO ratio in the tail gas was 87.2%, 54.4%, 65.2%, 43.0%, and 1.17 respectively at 750 °C over the optimized MCNi 0.51Mg 0.49O (the ratio was 0.51:0.49 with 8.3 wt% NiO loading amount) during 60 h of time on stream (TOS). And the formation of NiO–MgO solid solution structure would restrain the active Ni 0 centers from agglomeration and decrease carbon deposition. Cold test of the vertical-placed tubular reformers (packed by monolith of 7 mm cell spacing) indicated that the pressure drop was as low as 850 Pa at 1.57 m/s of gas velocity with 330 g/m 3 fly ash added. The reforming of real biomass fuel gas (H 2/CO/C 2H 4/CH 4/CO 2/N 2 = 10.2/16.8/0.5/6.4/15.2/51.0, vol.%, from air gasification of 200–250 kg/h pine sawdust in the pilot plant) in the multi-tube reformer packed with MCP (larger in size than MCNi 0.51Mg 0.49O) exhibits the pressure drop of less than 700 Pa, CH 4 and CO 2 conversions of about 84% and 38.5% and the decrease of tar content from 4.8–5.3 g/m 3 to 0.12–0.14 g/m 3 during 60 h TOS at 670 °C. The characterization of the spent catalysts by TG, XRD and ICP-AES proved the anti-sintering and anti-carbon deposition properties of NiO–MgO solid solution monolithic catalyst.