全新的一步甲酸辅助固相研磨法制备高活性的金属Cu/ZnO催化剂用于低温甲醇合成反应的研究

Metallic catalysts (Cu/ZnO) and pure metals (Co, Ni and Ag) without any impurity are directly prepared by a novel formic acid assisted solid-state method without further reduction. During the decomposition of metal-formic acid precursors at 523 K in an argon atmosphere, H2 and CO are liberated and act in situ as reducing agents to obtain pure metals and metallic catalysts (Cargon). The X-ray diffraction, X-ray photoelectron spectroscopy, Energy Dispersive Spectroscopy, and Temperature-Programmed Reduction analysis reveal that as-prepared catalyst Cargon without further reduction is converted into metallic Cu and ZnO species. TPR analysis results, Fourier Transform-Infrared analysis and the thermal decomposition behavior in air illustrate that no amorphous carbon or carbonic residues are left in Cargon using formic acid as chelating agent and reductant, because formic acid is the simplest organic acid with no C-C covalent bonds. The as-prepared Cu/ZnO catalyst is tested for low-temperature methanol synthesis at 443 K from syngas containing CO2 and using ethanol as a solvent and catalyst, which exhibits much higher activity and methanol selectivity than those prepared by conventional solid-state methods. Study on fix-bed technology instead of slurry phase for low-temperature methanol synthsis with achols as solvent and catalysts. Mass transfer of reatant is strengthed, meanwihle, heat transfer is also promoted. One pass conversion of ICI plant is limited to only 14%. For slurry phase low-temperature methanol synthesis, one pass conversion of CO is about 35%. For this promoted fix-bed low-tempereture methanol synthesis, tha activity is about 70%, nearly getting to the thermodynamic equelibrium.

本课题提出一种全新的甲酸辅助固相研磨法一步制备金属Cu/ZnO催化剂和纯金属（Co,Ni和Ag）。所制备的金属催化剂无任何含碳有机物及无定型碳剩余。当固相研磨后形成的金属-甲酸螯合物前驱体在氩气条件下分解过程中，逐步释放出氢气和一氧化碳。在523 K,氢气和一氧化碳作为还原剂能够把二价铜离子从螯合物中还原为金属铜。XRD,EDS,TPR,XPS等多种表征手段充分证明所制备的催化剂为金属Cu和ZnO，无任何杂质存在。所制备的Cu/ZnO催化剂直接用于低温甲醇合成反应，而不经过额外的还原。相比较常规固相研磨法制备的还原后的催化剂，这种新方法制备的催化剂表现出较高的活性以及甲醇选择性。拟研究内容二，改进现有的浆态床低温甲醇合成工艺为固定床工艺，同时作为溶剂和催化剂存在的醇溶剂以微量泵打入固定床反应器。采用固定床工艺，反应物与催化剂之间的传质能够加强，同时醇溶剂作为传热剂和取热剂的作用也得到加强。

经过该项目资助，我们成功开创了一种全新的甲酸辅助固相研磨法一步制备高活性的金属Cu/ZnO催化剂和Co/SiO2催化剂，以及纯金属（Co,Ni和Ag）。我们所制备的金属催化剂中无任何含碳有机物及无定型碳剩余。其还原机理是：当固相研磨后形成的金属-甲酸螯合物前驱体在氩气条件下分解过程中，逐步释放出氢气和一氧化碳。在523 K,氢气和一氧化碳作为还原剂能够把二价铜离子从螯合物中还原为金属铜。XRD,EDS,TPR,XPS等多种表征手段充分证明所制备的催化剂为金属Cu和ZnO，无任何杂质存在。所制备的Cu/ZnO催化剂直接用于低温甲醇合成反应，而不经过额外的还原。相比较常规固相研磨法制备的还原后的Cu/ZnO催化剂，这种新方法制备的催化剂表现出较高的活性以及甲醇选择性。同时，我们改进现有的浆态床低温甲醇合成工艺为固定床工艺，把作为溶剂和催化剂存在的醇溶剂以微量泵打入固定床反应器。大量实验结果表明，采用固定床工艺，反应物与催化剂之间的传质能够加强，同时醇溶剂作为传热剂和取热剂的作用也得到加强。.采用柠檬酸辅助法制备的Co/SiO2催化剂，其中金属Co晶粒大小仅为2-3纳米，在费托合成反应中表现出极高的反应活性，为常规浸渍法制备的催化剂活性的4倍。.经过项目资助，2014-2016共发表带有标注的SCI收录论文6篇，EI收录论文1篇，申请专利20余项目，授权专利9项。