用于低温液相合成甲醇的新型铜基催化剂的研究
文献类型：学位论文
| 作者 | 李源 |
| 学位类别 | 硕士 |
| 答辩日期 | 2010-05-29 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 张锁江 |
| 关键词 | 低温液相 甲醇 合成气 铜基催化剂 |
| 其他题名 | Study on a new Copper-based Catalyst Cu/MgO/ZnO for Low-temperature methanol synthesis |
| 学位专业 | 应用化学 |
| 中文摘要 | 甲醇是一种极其重要的化工基础原料，也是一种极具潜力的车用燃料和燃料电池的原料。在工业上，甲醇的生产主要采用气相法，以合成气为原料，在高温、高压条件下，使用Cu/ZnO基催化剂催化合成，但该工艺存在CO单程转化率低且循环能耗大等缺点。有研究在373~403 K及1.0~5.0 MPa的条件下，在液相环境中实现了低温甲醇的合成，取得了良好的结果。但由于催化剂体系中如CH3ONa等的羰基催化剂对微量的水及二氧化碳极其敏感，催化剂体系很快失活，因此工业化非常困难。本文针对以上问题，首先以Cu/MgO及Cu/MgO/ZnO两种铜基催化剂为研究对象，考察了影响催化剂性能的因素，优化了催化剂制备条件；利用XPS、TPR、XRD等手段对催化剂进行表征，分析了MgO对催化剂活性中心的影响。其次采用Cu/MgO/ZnO催化剂，考察了工艺条件对低温液相合成甲醇的影响。在不添加羰基催化剂的条件下，取得了良好的结果。通过研究，本文得到以下主要结论： (1)制备Cu/MgO催化剂的较优条件为pH=10.0，Cu/Mg=1:1，此时CO转化率为15.95%，甲醇选择性与时空收率分别为63.91%与0.8369 mol/(kg·h)。 (2)在较高的沉淀pH值下，催化剂中MgO可抑制CuO的还原，使得经还原后的催化剂中仍残留一定量的CuO；同时也可促进催化剂生成一定量的Cu+。 (3)同Cu/MgO催化剂中MgO的作用类似，在Cu/MgO/ZnO催化剂中，MgO的存在可促使催化剂生成Cu+，除此之外还有利于促进Cu0、Cu+在载体中的分散，且MgO引入活性中心Cu+的正面作用大于其阻碍CuO还原减少还原Cu的负面作用。 (4)在Cu/MgO/ZnO催化剂中，当Cu/(Mg+Zn)=1:1，Mg/Zn=1:1，共沉淀温度为65℃，煅烧温度和时间分别为350℃与2 h时，催化剂活性最好，CO转化率达到63.56%，甲醇选择性与时空收率分别为99.09%与5.413 mol/(kg·h)。 (5)采用Cu/MgO/ZnO催化剂对浆态床反应器合成甲醇的条件进行了优化，优化的反应温度为443 K；在实验范围内优化的搅拌转速为700 r/min；随着反应压力由2 MPa升高到5 MPa，CO的转化率由24.29%提高至60.28%，甲醇的时空收率由2.057 mol/(kg·h)提高至6.070 mol/(kg·h)。 |
| 英文摘要 | Methanol is one of the primary chemicals for industries, vehicle fuel and fuel cells. It is commercially produced from syngas under high temperature and high pressure with Cu/ZnO-based catalyst. Under the reaction condition, one-pass conversion of CO is very low due to the thermodynamic limitation which makes recycle of unreacted syngas necessary and expensive. Some researches have realized low-temperature methanol synthesis in liquid phase at 373~403 K and 1.0~5.0 MPa with high catalytic activity. However, the deactivation of the catalytic system by trace amount of CO2 and H2O makes it hard to be industrialized. In the present work, a new kind of copper-based catalyst Cu/MgO/ZnO was prepared and studied. Series of Cu/MgO and Cu/MgO/ZnO catalyst were prepared by changing preparation conditions, and the optimized condition was obtained. The catalysts were characterized by XPS, TPR, XRD, and the effect of MgO on the catalytic active sites was discussed. Cu/MgO/ZnO was selected for methanol synthesis in the slurry reactor to optimize the processing conditions. Favorable results were obtained without using carbonylation catalyst. Conclusions were drawn as follows: (1) The optimized preparation conditions for Cu/MgO catalyst were co-precipitation pH=10.0 and Cu/Mg=1:1 while the conversion of CO, selectivity and space time yield of methanol reached 15.95%,63.91 and 0.8369 mol/(kg·h) respectively. (2) Under high co-precipitation pH value, CuO and Cu2O were both found in the reduced Cu/MgO catalyst, which means that MgO could suppress the reduction of CuO. (3) Similar to Cu/MgO catalyst, MgO could also introduce more Cu+ sites into Cu/MgO/ZnO catalyst. Besides, MgO promoted the dispersion of Cu0 and Cu+ in MgO/ZnO, which makes the catalyst more active than Cu/ZnO. Thus we conclude the positive effect of MgO is superior to its side-effect. (4) The optimized preparation conditions for Cu/MgO/ZnO catalyst were Cu/(Mg+Zn)=1:1, Mg/Zn=1:1, co-precipitation temperature 65 ℃, calcinations temperature 350 ℃ and calcinations time 2 h. The optimized catalyst could increase CO conversion, electivity and space time yield of methanol to 63.56%, 99.09% and 5.413 mol/(kg·h) respectively. (5) Using Cu/MgO/ZnO catalyst, the operation conditions were optimized in the slurry reactor, and the best operating temperature was 170 ℃. CO conversion and the space time yield (STY) of methanol increased noticeably with the increase of the pressure and stirring speed. |
| 公开日期 | 2013-09-17 |
| 页码 | 87 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1522]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 李源. 用于低温液相合成甲醇的新型铜基催化剂的研究[D]. 北京. 中国科学院研究生院. 2010. |
入库方式： OAI收割
来源：过程工程研究所
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