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Bimetallic Ni-M (M = Co, Cu and Zn) supported on attapulgite as catalysts for hydrogen production from glycerol steam reforming
Applied Catalysis A: General ( IF 5.5 ) Pub Date : 2017-11-21 , DOI: 10.1016/j.apcata.2017.11.014
Yishuang Wang , Mingqiang Chen , Zhonglian Yang , Tian Liang , Shaomin Liu , Zhongshan Zhou , Xiaojing Li

Monometallic Ni and bimetallic Ni-Co, Ni-Cu, and Ni-Zn catalysts supported on attapulgite (ATP) were prepared by chemical precipitation method and evaluated in the glycerol steam reforming (GSR) reaction under the following conditions W/G = 9, N2 flow ratio = 0.16 L/min and GHSV = 9619 h−1. The prepared calcined and/or reduced samples were characterized by ICP-OES, N2 adsorption-desorption, XRD, TEM, FT-IR, XPS and H2-TPR. The analysis results showed the addition of second metals obviously decreased the crystal size and suppressed the reducibility of active metal, by improving the metal-support interaction. These were optimized characters could promote the steam reforming reaction and water-gas shift reaction (WGSR) to improve the catalytic performance. The experimental results of catalytic activity revealed the glycerol conversions and H2 yields over bimetallic catalysts were significantly higher than those over Ni/ATP catalyst. Among them, the Ni-Cu/ATP exhibited the highest the highest glycerol conversions and H2 yield in GSR reaction, while it had larger particle size (12.2 nm) than Ni-Co/ATP (8.6 nm) and Ni-Zn/ATP (10.3 nm), and the higher reducibility than other two bimetallic catalysts. It may be deduced that the crystal size and reducibility of catalyst all showed pivotal to impart suitable catalytic activity, while these characteristics should have an optimal proportion for obtaining the outstanding catalytic performance. The effect of temperature on catalytic performance over all catalysts was also investigated. It was found that increasing temperature was favorable for glycerol conversions and H2 yield, while the increase rate of H2/CO ratio was suppressed and CO/CO2 ratio were increased for all catalysts at high temperature range of 600–700 °C. It was attributed to that increasing temperature although improved the breakage of CC, CH, and CO bonds in glycerol, the WGSR mainly side-reaction for producing H2 was suppressed. The long-term experiments (30 h) were also conducted over all catalysts at W/G = 9, T = 600 °C, N2 flow ratio = 0.16 L/min and GHSV = 9619 h−1. The results demonstrated the outstanding stability was obtained over Ni-Zn/ATP catalyst. In order to account for the causes resulted in catalyst deactivation, all spent catalysts were characterized by XRD, TEM, TPO and TG-DTG. The results shown catalyst deactivation was mainly affected by the sintering of active species and coke formation on catalyst surface. The Ni-Zn/ATP bimetallic catalyst showed the outstanding stability attributed to the excellent anti-sintering and carbon deposition, which resulted from the formation of unique metal-support interaction.



中文翻译:

凹凸棒石上负载的双金属Ni-M(M = Co,Cu和Zn)作为甘油蒸汽重整制氢的催化剂

通过化学沉淀法制备负载在凹凸棒石(ATP)上的单金属Ni和双金属Ni-Co,Ni-Cu和Ni-Zn催化剂,并在以下条件W / G = 9的条件下,通过甘油蒸汽重整(GSR)反应对其进行评估。 N 2流量比= 0.16L / min,GHSV = 9619h -1。通过ICP-OES,N 2吸附-解吸,XRD,TEM,FT-IR,XPS和H 2表征制备的煅烧和/或还原的样品-TPR。分析结果表明,通过改善金属-载体的相互作用,添加第二种金属明显降低了晶体尺寸并抑制了活性金属的还原性。这些优化的特征可以促进蒸汽重整反应和水煤气变换反应(WGSR),以提高催化性能。催化活性的实验结果表明,双金属催化剂的甘油转化率和H 2收率明显高于Ni / ATP催化剂。其中,Ni-Cu / ATP的甘油转化率最高,H 2含量最高。在GSR反应中获得了高收率,但其粒径(12.2 nm)比Ni-Co / ATP(8.6 nm)和Ni-Zn / ATP(10.3 nm)大,并且比其他两种双金属催化剂具有更高的还原性。可以推断出,催化剂的晶体尺寸和还原性均显示出关键性,以赋予适当的催化活性,而这些特性应具有最佳比例以获得优异的催化性能。还研究了温度对所有催化剂的催化性能的影响。发现升高温度有利于甘油转化和H 2产率,同时抑制了H 2 / CO比的增加速率并且抑制了CO / CO 2。在600–700°C的高温范围内,所有催化剂的比值均增加。这归因于温度的提高,尽管改善了甘油中C C,C H和C O键的断裂,但WGSR主要用于产生H 2的副反应得到了抑制。还在W / G = 9,T = 600°C,N 2流量比= 0.16 L / min和GHSV = 9619 h -1的条件下对所有催化剂进行了长期实验(30 h)。结果表明,在Ni-Zn / ATP催化剂上具有优异的稳定性。为了解决导致催化剂失活的原因,对所有用过的催化剂进行了XRD,TEM,TPO和TG-DTG表征。结果表明,催化剂失活主要受活性物质的烧结和催化剂表面焦炭形成的影响。Ni-Zn / ATP双金属催化剂具有出色的稳定性,这归因于出色的抗烧结和碳沉积,这是由于独特的金属-载体相互作用形成的结果。

更新日期:2017-11-21
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