Low-temperature partial oxidation of ethanol on Ni/ZnO catalyst

N. V. Lapin, V. Grinko, V. S. Bezhok, A. Vyatkin
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Abstract

The paper investigates the partial oxidation of ethanol process in a quartz microreactor at atmospheric pressure in the temperature range 300–450 °C on a nickel catalyst (20 wt%) deposited on zinc oxide. Rectified ethanol (an azeotropic mixture of 95.6 wt.% ethanol and 4.4 wt.% water) is fed into the reactor at a rate of 0.4–1.3 g / hour by a peristaltic pump, first into the evaporator, and then as a gas phase into the reactor. Air is used as a source of oxygen which is supplied by an air pump to the reactor and its flow is controlled by a rotameter so that the oxygen-ethanol molar ratio varied between 0.45 and 2.0. The nickel catalyst is prepared by impregnating industrial zinc oxide powder with nickel nitrate, followed by calcination and reduction of nickel oxide to metallic nickel. Analysis of gaseous products is performed on a Tsvet-500 gas chromatograph. The detector is a katharometer.A catalyst Ni/ZnO developed earlier is shown to have high efficiency in the partial oxidation of ethanol at low temperatures. The main products of this process are hydrogen, methane, carbon monoxide and dioxide. With an increase in the oxygen-ethanol molar ratio, the hydrogen content in the products of the process decreases (from 60 to 25 vol.%), carbon dioxide, on the contrary, increases (26 to 65 vol.%). The hydrogen yield is 1 mol per 1 mol of ethanol at a temperature of 450 °C.Carbon monoxide is observed with a low ratio of oxygen-ethanol (up to 0.85). With a higher ratio, carbon monoxide is absent in the entire temperature range studied. The conversion of ethanol proceeds intensively and already at a temperature of 450 °C ethanol is converted almost completely. A high methane content (20–30% vol.%) in reforming products indicates that the initial stage of the process is the oxidation of ethanol followed by decomposition of the resulting acetaldehyde into methane and carbon monoxide.The insignificant water content in the supply mixture leads to an almost complete absence of a shift reaction. Carbon monoxide is then oxidized with oxygen to carbon dioxide. The reduced methane content in comparison with the process of water-steam ethanol reforming can be explained by its partial oxidation to carbon dioxide, which explains the high content of the latter in reforming products. 
乙醇在Ni/ZnO催化剂上的低温部分氧化
本文研究了在常压300-450°C的石英微反应器中,在氧化锌上沉积镍催化剂(20% wt%)的部分氧化过程。精馏乙醇(95.6 wt.%乙醇和4.4 wt.%水的共沸混合物)通过蠕动泵以0.4-1.3 g /小时的速率进入反应器,首先进入蒸发器,然后作为气相进入反应器。空气作为氧气的来源,由气泵提供给反应器,其流量由转子流量计控制,因此氧与乙醇的摩尔比在0.45和2.0之间变化。采用硝酸镍浸渍工业氧化锌粉,煅烧还原氧化镍制得金属镍的方法制备镍催化剂。气体产物的分析在Tsvet-500气相色谱仪上进行。这个探测器是一个温度计。研究表明,Ni/ZnO催化剂在低温条件下对乙醇的部分氧化具有较高的效率。这一过程的主要产物是氢气、甲烷、一氧化碳和二氧化碳。随着氧-乙醇摩尔比的增加,该过程产物中的氢含量减少(从60%到25vol .%),相反,二氧化碳含量增加(从26%到65vol .%)。在450℃下,氢的产率是1 mol / 1 mol乙醇。一氧化碳在低氧乙醇比(高达0.85)下被观察到。在较高的比例下,一氧化碳在整个温度范围内都不存在。乙醇的转化进行得很快,在450°C的温度下,乙醇几乎完全转化。重整产物中的高甲烷含量(20-30% vol.%)表明该过程的初始阶段是乙醇的氧化,然后将产生的乙醛分解成甲烷和一氧化碳。供应混合物中微不足道的水含量导致几乎完全没有移位反应。然后一氧化碳与氧气氧化成二氧化碳。与水-蒸汽乙醇重整相比,甲烷含量的降低可以解释为其部分氧化为二氧化碳,这解释了重整产物中二氧化碳含量高的原因。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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