合成气制低碳醇Cu-Fe催化剂的制备及改性机制研究

发布时间：2018-02-25 18:00

  本文关键词： 合成气 低碳醇 CTAB-MnCuFe/ZnO Cu-Fe_3C 工艺参数　出处：《华东理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：合成气催化制备低碳醇是综合利用煤、天然气及生物质等能源的有效方法之一。通过对费托合成催化剂的改性来提高低碳醇选择性及时空收率是此课题研究的重要方向。本研究以Cu-Fe催化剂为基础,考察了 CeO、ZrO_2、Al2O3、MgO和ZnO载体,非碱性金属 Al、Ce、La、Mg、Ba、Ca、Zr、Cr、Mn、Ti、Co 和 Ni 助剂以及表面活性剂 CTAB、PVP、PEG和SDS对催化剂性能的影响,属ZnO、Mn和CTAB改性效果最佳。继而,采用BET、SEM、XRD、TPR、XPS等表征手段研究了三者的改性机制,确定反应的活性中心。研究表明,ZnO载体大大改变了催化剂的物理结构,促进了活性组分的分散及其还原能力,低碳醇时空收率为载体中最佳的46mg·L~(-1)·h~(-1)。Mn作为改性效果最佳的金属助剂,促使高度聚集的CuFe_2O_4分裂形成ZnFe_2O_4和CuMn_2O_4,并在预处理过程中彻底还原成分子态Fe和Cu,形成合成气催化反应所需的Cu-Fe_3C双活性位,改性后低碳醇选择性及时空收率分别达到了 52%和102mg·L~(-1)·h~(-1)。此外,CTAB改性后低碳醇选择性提升至56%,其添加强化了 CuO的还原力,Cu0/Cu+比例明显提高,Cu-Fe_3C双活性位之间的作用力增强。同时,对MnCuFe/ZnO及CTAB-MnCuFe/ZnO催化剂制备及操作参数的研究表明,450℃的煅烧温度、300℃的反应温度、H2/CO = 2.0的原料配比对低碳醇的制备最有利。
[Abstract]:Synthesis of low carbon alcohols catalyzed by syngas is a comprehensive utilization of coal. One of the effective methods for energy sources, such as natural gas and biomass, is to improve the selectivity and space-time yield of low carbon alcohols by modifying Fischer synthesis catalysts. This research is based on Cu-Fe catalysts. The effects of CEO _ 2O _ 2Al _ 2O _ 3 MgO and ZnO supports, non-alkaline metal Altrocerium laurantium, baccalcium zirconium, and Ni additives, as well as surfactants such as CTABX, PVP, PEG and SDS, on the catalytic properties of the catalysts were investigated. The modification mechanisms of the three catalysts were studied by means of BET-SEMXRDX TPR-TPR-XPS, and the effects of CTAB / ZrO2Al2O3-MgO and SDS on the performance of the catalysts were investigated. The results showed that ZnO support greatly changed the physical structure of the catalyst, promoted the dispersion of active components and their reduction ability, and the space-time yield of low carbon alcohol was the best 46mg 路L ~ (-1) 路hu ~ (-1) 路mn as the metal adjuvant with the best modification effect. The highly aggregated CuFe_2O_4 splits into ZnFe_2O_4 and CuMn2O4, and in the process of pretreatment, the molecular Fe and Cu are completely reduced to form the double active sites of Cu-Fe_3C for the catalytic reaction of syngas. After modification, the selectivity and space-time yield of low carbon alcohols reached 52% and 102 mg 路L ~ (-1) 路h ~ (-1) 路h ~ (-1) respectively. In addition, the selectivity of low carbon alcohols was increased to 56% after modified by CuO. The ratio of Cu _ 0 / Cu _ 0 / Cu to Cu _ 0 / Cu _ 0 / Cu _ 2O _ 2 enhanced the interaction force between Cu _ Fe _ 3C and Cu _ 2O _ 3. The preparation and operation parameters of MnCuFe/ZnO and CTAB-MnCuFe/ZnO catalysts were studied. The results show that the ratio of H _ 2 / CO = 2.0 is the most favorable for the preparation of low carbon alcohols at the calcination temperature of 450 鈩，

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