| dc.description.abstract | The plasma modification of the catalyst is a novel way to improve performance of catalyst. Such prepared catalyst presents a higher catalytic activity and an enhanced stability over the catalyst prepared without plasma treatment. This study aims to evaluate the characteristics of Ni/Al2O3 catalyst for steam reforming of ethanol to syngas via a DBD by different flowing gases and with different processes. DBD reactor is made of the quartz tube with the inner diameter of 10.6 mm. A stainless steel rod with the diameter of 0.1 mm is used as the inner electrode and the length of discharge region is 100.0 mm. Experimental tests are conducted at fixed applied voltage (16 kV), frequency (100 Hz), applied energy of catalyst (10800 J/g), space velocity (1498 hr-1) and temperature (25 ℃), while the flowing gases include hydrogen and oxygen, the processes include discharge before and after calcination. Steam reforming experimental tests are conducted at fixed space velocity (10602 hr-1), ethanol-water mole ratio (1:3), while the temperature vary from 446 ℃ to 736 ℃.
The catalyst prepared with discharge before calcination exhibits lower ethanol conversion rate and hydrogen selectivity, compared to the catalyst prepared without plasma treatment. At 446 ℃, ethanol conversion efficiency of traditional, O2 plasma and H2 plasma catalyst are 82.6%, 61.9% and 57.1%, H2 selectivities of each one are 42.9%, 22.8% and 0.0%, respectively. At 736 ℃, ethanol conversion efficiency of each catalyst reaches to above 99.0%, H2 selectivities of traditional, O2 plasma and H2 plasma catalyst are 85.7%, 71.6% and 83.0%, respectively. At another case, the catalyst prepared with discharge after calcination by H2 plasma shows improved ethanol conversion rate and hydrogen selectivity, compared to O2 plasma and tranditional catalyst. At 446 ℃, ethanol conversion efficiency of O2 plasma and H2 plasma catalyst are 56.9%, 39.2% and 60.4%, the H2 selectivities of each one are all 0.0%. At 736 ℃, the ethanol conversion efficiency of each catalyst reach above 99.0%, H2 selectivities of traditional, O2 plasma and H2 plasma catalyst are 51.7%, 39.9% and 72.5%, respectively. In order to reduce the effect of coke formation, the catalyst discharged after calcination conducts steam reforming process by temperature decrease way, at 446 ℃, ethanol conversion efficiency of traditional, O2 plasma and H2 plasma catalyst are 79.0%, 66.9% and 90.6%, H2 selectivities of each one are 42.8%, 64.5%, 37.4%, respectively. At 736 ℃, ethanol conversion efficiency of each catalyst are able to reach to above 99.0%, H2 selectivities of each one are 42.8%, 64.5%, 37.4%, respectively. 87.0%, 82.3%, 92.8%.
The present investigation confirms the DBD treatment of Ni/γ-Al2O3 catalyst with hydrogen after calcination thermally, leads to better activity and selectivity for steam reforming of ethanol to syngas.
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