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Effect of CO_2 in the synthesis of mixed alcohols from syngas over a K/Ni/MoS_2 catalyst

机译：K_2 / Ni / MoS_2催化剂上CO_2对合成气合成混合醇的影响

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摘要

An unsupported K-Ni-MoS_2 catalyst for higher alcohol synthesis from syngas (H_2/CO) has been studied during 360 h on stream. It shows a gradual increase in activity with time on stream and some possible reasons for this are discussed in the paper. The main focus of this paper was to study the on the effect of CO_2-containing syngas, relative CO_2-free syngas under identical reaction conditions and identical inlet H_2 and CO partial pressures (340 ℃, 100 bar, GHSV = 6920 ml/(g_(cat) h)). The effect of increased partial pressure of H_2 and CO was also studied, and to a minor extent also the effect of changed gas hourly space velocity (GHSV). Under the studied conditions, addition of CO_2 was found to greatly decrease total product yield, while the selectivities to alcohol and hydrocarbons (C%, CO_2-free), respectively, were unchanged. CO_2 addition, however, led to a great change in the distribution within the alcohol and hydrocarbon groups. With CO_2 added the methanol selectivity increased much while selectivity to longer alcohols decreased. For hydrocarbons the effect is the same, the selectivity to methane is increased while the selectivity to longer hydrocarbons is decreased. It has earlier been shown that product selectivities are greatly affected by syngas conversion level (correlated to outlet concentration of organic products, i.e. alcohols, hydrocarbons etc.) which can be altered by changes in space velocity or temperature. This means that alcohol selectivity is decreased in favor of increased hydrocarbon selectivity and longer alco-hol-to-methanol ratio when syngas conversion is increased. At first it might be thought that the selectivity changes occurring when CO_2 is present in the feed, just correlate to a decreased organic product concentration in the reactor and that the selectivities with CO_2-containing and CO_2-free syngas would be identical under constant concentration of organic products in the reactor. However, CO_2-addition studies where space velocity was varied showed that significantly lower alcohol selectivity (mainly eth-anol selectivity) and increased hydrocarbon selectivity (mainly methane) were found at similar organic outlet concentrations as when CO_2-free syngas was feed. Comparing addition of extra H_2 or extra CO, it was found that a high H_2/CO ratio (H_2/CO = 1.52 tested in our case) favors maximum product yield, especially methanol formation, while a lower H_2/CO ratio (H_2/CO - 0.66 tested in our case) leads to higher yield of higher alcohols simultaneously minimizing hydrocarbon and methanol formation.
机译：在运行过程中的360小时内，研究了无载体的K-Ni-MoS_2催化剂，用于从合成气（H_2 / CO）合成高级醇。它显示了活动随着时间的推移逐渐增加，并在本文中讨论了一些可能的原因。本文的主要重点是研究在相同的反应条件和相同的入口H_2和CO分压（340℃，100 bar，GHSV = 6920 ml /（g_）下，相同反应条件下含CO_2的合成气，相对不含CO_2的合成气的影响。 （cat）h））。还研究了H_2和CO分压增加的影响，并在较小程度上还研究了气时空速变化（GHSV）的影响。在研究的条件下，发现添加CO_2会大大降低总产品收率，而对醇和烃的选择性（C％，无CO_2）则保持不变。然而，CO_2的添加导致醇和烃基团内分布的巨大变化。加入CO_2后，甲醇的选择性大大提高，而对较长醇的选择性降低。对于烃，效果是相同的，增加了对甲烷的选择性，同时减少了对较长烃的选择性。早先已经表明，产物的选择性受合成气转化率的影响很大（与有机产物的出口浓度有关，即醇，碳氢化合物等），而合成气的转化率可以通过空速或温度的变化而改变。这意味着当合成气转化率提高时，醇的选择性降低，有利于碳氢化合物的选择性提高和更长的醇-醇-甲醇比。首先，可以认为当进料中存在CO_2时选择性发生变化，这仅与反应器中有机物浓度的降低有关，并且在CO2恒定浓度下含CO_2和不含CO_2的合成气的选择性相同。反应器中的有机产物。但是，在空速变化的情况下进行的CO_2加成研究表明，在与不含CO_2的合成气进料相似的有机出口浓度下，发现醇选择性（主要是乙醇选择性）显着降低，而烃选择性（主要是甲烷）升高。比较添加额外的H_2或额外的CO，发现高的H_2 / CO比（在我们的案例中测试为H_2 / CO = 1.52）有利于最大的产品收率，尤其是甲醇生成，而较低的H_2 / CO比（H_2 / CO -在我们的案例中经过测试为0.66）可导致更高的高级醇收率，同时最大程度地减少碳氢化合物和甲醇的形成。

著录项

  • 来源
    《Fuel》 |2013年第5期|715-723|共9页
  • 作者

    Robert Andersson; Magali Boutonnet; Sven Jaeras;

  • 作者单位

    Royal Institute of Technology (KTH), Department of Chemical Engineering and Technology, Chemical Technology, Teknikringen 42, SE-100 44 Stockholm, Sweden;

    Royal Institute of Technology (KTH), Department of Chemical Engineering and Technology, Chemical Technology, Teknikringen 42, SE-100 44 Stockholm, Sweden;

    Royal Institute of Technology (KTH), Department of Chemical Engineering and Technology, Chemical Technology, Teknikringen 42, SE-100 44 Stockholm, Sweden;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    syngas; higher alcohols; MoS_2; CO_2-containing syngas; synthetic fuels;

    机译：合成气高级酒精MoS_2;含CO_2的合成气;合成燃料;

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