共查询到18条相似文献,搜索用时 171 毫秒
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碳酸二甲酯与苯酚酯交换合成碳酸二苯酯研究 总被引:6,自引:0,他引:6
选择Lewis酸催化剂、分子筛催化剂、有机钛和锡化合物催化剂和不同负载型金属氧化物催化剂用于碳酸二甲酯(DMC)与苯酚酯交换合成碳酸二苯酯(DPC)的过程。试验结果表明,:MoO3/SiO2和TiO2/SiO2催化剂对该反应具有相对较好的催化活性和选择性。以MoO3/SiO2为催化剂,DMC转化率和DPC选择性分别为24.3%和37.6%;以TiO2/SiO2,为催化剂,DMC转化率和DPC选择性分别为13.7%和20.0%。在该酯交换反应中,SiO2与Al2O3和MgO相比,是一种良好的催化剂载体。 相似文献
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以硝酸锆为锆源、硝酸铝为铝源,采用共沉淀法制备了Al2O3-ZrO2复合载体,通过MoO3改性和H2SO4浸渍法制备了MoO3改性的SO2-4/Al2O3-ZrO2催化剂.用XRD和FT-IR对催化剂进行表征,用元素分析仪测定硫含量,用乙酸和正丁醇的酯化反应对其催化活性进行考察.结果发现,当MoO3添加质量分数达12.0%时,出现MoO3衍射峰,表明适当的MoO3可以单层分布在催化剂表面,从而稳定SO2-4的存在.FT-IR分析结果表明,催化剂具有固体酸的特征峰.在MoO3添加质量分数为8.0%和焙烧温度650 ℃时,催化剂的催化活性达最大值,催化活性与硫含量的增加不一致. 相似文献
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MoO3/γ-Al2O3在四氢糠醇合成吡啶中的应用 总被引:1,自引:1,他引:0
研究了以四氢糠醇(THFA)和氨气为原料,MoO3/-γA l2O3为催化剂经气固相接触催化合成吡啶的反应。采用XRD、XPS、BET对催化剂进行了表征,气相色谱-质谱联用仪对反应产物进行了分析,确定了主产物吡啶。考察了反应温度、MoO3负载量、四氢糠醇流量、催化剂用量对反应的影响。结果表明,负载量为10%的MoO3/γ-A l2O3经固定床反应器,反应温度为500℃,n(THFA)∶n(NH3)=1∶5时,四氢糠醇的转化率达95.47%,吡啶的选择性达74.82%,吡啶的收率达71.44%。 相似文献
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以氢氧化钠为沉淀剂,硝酸铜、硝酸锌、硝酸铝和硝酸氧锆为原料,采用共沉淀法制备出了用于二乙醇胺脱氢制亚氨基二乙酸的Cu/ZnO/Al2O3/ZrO2催化剂,并用物理吸附(BET)和X射线衍射(XRD)对不同种类的铜基催化剂进行了表征,探讨了ZnO和Al2O3的不同比例对催化剂性能的影响。结果表明,同时加入ZnO和Al2O3的Cu/ZnO/Al2O3/ZrO2催化剂具有大的比表面积,Cu/ZnO/Al2O3/ZrO2催化剂具有非晶态结构。该催化剂适宜的反应条件为:w(NaOH)=30%、反应温度160℃、压力1.0 MPa,二乙醇胺转化率可达100%,亚氨基二乙酸收率可达95.61%。 相似文献
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以Al2O3/SiO2为催化剂考察了碳酸二甲酯和碳酸二乙酯在液相条件下酯交换合成碳酸甲乙酯的过程.研究了活性组分负载量、催化剂用量、反应温度、反应时间等条件对酯交换反应的影响,并通过NH3-TPD和N2吸附脱附等手段对催化剂进行了表征.结果表明:以SiO2为载体,Al2O3负载量为12%的催化剂对碳酸二甲酯与碳酸二乙酯... 相似文献
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In this work, NiMo catalysts with various contents of MoO_3 were prepared through incipient wetness impregnation by a two-step method(NM-x A) and one-pot method(NM-xB). The catalysts were then characterized by XRD, XPS, NH_3-TPD, H_2-TPR, HR-TEM, and N2 adsorption–desorption technologies.The performance of the NiMo/Al_2O_3 catalysts was investigated by hydrocracking low-temperature coal tar. When the MoO_3 content was 15 wt%, the interaction between Ni species and Al_2O_3 on the NM-15 B catalyst was stronger than that on the NM-15 A catalyst, resulting in the poor performance of the former.When the MoO_3 content was 20 wt%, MoO_3 agglomerated on the surface of the NM-20 A catalyst, leading to decreased number of active sites and specific surface area and reduced catalytic performance. The increase in the number of MoS_2 stack layers strengthened the interaction between Ni and Mo species of the NM-20 B catalyst and consequently improved its catalytic performance. When the MoO_3 content reached 25 wt%, the active metals agglomerated on the surface of the NiMo catalysts, thereby directly decreasing the number of active sites. In conclusion, the two-step method is suitable for preparing catalysts with large pore diameter and low MoO_3 content loading, and the one-pot method is more appropriate for preparing catalysts with large specific surface area and high MoO_3 content. Moreover, the NMx A catalysts had larger average pore diameter than the NM-xB catalysts and exhibited improved desulfurization performance. 相似文献
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Surface properties and catalytic behavior of MoO3/SiO2 in esterification of acetic acid with ethanol
Abd El‐Aziz A Said Mohamed MM Abd El‐Wahab 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(3):329-335
A series of MoO3/SiO2 catalysts was prepared by an impregnation method with Mo loadings ranging from 1 to 50 wt%. The original and calcined samples at 400 °C were characterized by thermogravimetry (TG), differential thermogravimetry (DTG), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), Fourier transform infra‐red (FTIR) spectroscopy, and nitrogen adsorption measurements. The surface acidity and basicity of the catalysts were investigated by the dehydration–dehydrogenation of isopropanol and the chemisorption of pyridine. The catalytic esterification of acetic acid with ethanol was carried out at 220 °C in a conventional fixed‐bed reactor at 1 atm using air as a carrier gas. The results clearly revealed that silica–molybdena catalysts were active and selective towards the formation of ethyl acetate. Moreover, the catalyst containing 20 wt% MoO3 was the most active and selective one. The results emphasize the importance of the surface acid sites together with the specific surface area of the prepared catalyst, towards ester formation. Copyright © 2005 Society of Chemical Industry 相似文献
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V2O5-MoO3/TiO2 催化剂的NOx选择性催化还原及SO2氧化活性 总被引:2,自引:0,他引:2
采用浸渍法以TiO2为载体制备V2O5-MoO3/TiO2 选择性催化还原催化剂,研究V2O5和MoO3负载量对于催化剂选择性催化还原反应及SO2氧化活性的影响,并考察氧含量、氨氮物质的量比和反应空速对3%V2O5-6%MoO3/TiO2催化剂选择性催化还原脱硝活性的影响。结果表明,随着催化剂中V2O5负载质量分数增加,V2O5-MoO3/TiO2 催化剂的选择性催化还原活性和SO2氧化活性均呈上升趋势。MoO3的负载对催化剂的SO2氧化活性有明显抑制作用。MoO3负载质量分数超过9%,制备的催化剂既保持较高的低温选择性催化还原活性,又使选择性催化还原反应中的SO2转化率小于1%。 相似文献
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以硝酸铜、硝酸锌等为原料,采用沉淀-沉积法制备了载体是介孔Al_2O_3的CuO/ZnO/Al_2O_3催化剂,通过改变焙烧时间可得到不同活性组分形貌(团簇球状和棒状)的催化剂,并用于CO/CO_2加氢反应。通过XRD、BET、N_2吸附-脱附、TEM、H_2-TPR、CO_2-TPD、NH_3-TPD和FTIR对催化剂进行了表征与测试。结果表明,活性组分(CuO/ZnO)形貌的改变影响了催化剂的Cu O晶粒尺寸、比表面积、孔径及其还原性能,且对催化剂的酸性位点和碱性位点的相对数量影响较大。团簇球状催化剂中活性组分的分散度高、易还原、碱性位多、酸性位少,有利于甲醇的生成;而棒状催化剂中孔道不均匀、碱性位少、酸性位多,更有利于二甲醚(DME)的生成。活性测试结果表明,团簇球状催化剂表现出高甲醇选择性(95.05%)和低DME选择性(4.18%);棒状催化剂的产物选择性与团簇球状相反,表现出高DME选择性(75.41%)和低甲醇选择性(12.81%)。 相似文献
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为了获得高水热稳定的负载Ni催化剂,延长催化剂在含水液相体系中的使用寿命,以不同温度焙烧的SiO2-Al2O3为载体,采用浸渍法制备Ni/SiO2-Al2O3催化剂,通过吡啶-原位傅立叶变换红外光谱、X射线衍射、NH3-程序升温脱附和H2-程序升温还原等方法进行表征,以水相1,4-丁炔二醇加氢为探针反应,研究载体焙烧温度对Ni/SiO2-Al2O3催化剂催化加氢性能及含水体系中稳定性的影响。结果表明,在(400~800) ℃,随着载体焙烧温度升高,活性组分Ni存在状态及催化剂加氢活性变化较小,但催化剂的水热稳定性下降,造成这一现象的原因是随着载体焙烧温度升高,载体表面SiO2聚集,暴露的Al3+增加,载体水合程度增大。载体焙烧温度400 ℃时,Ni/SiO2-Al2O3催化剂表现出最佳的水热稳定性。 相似文献
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采用浸渍-沉淀法制备Al2O3-ZrO2复合氧化物,通过程序升温还原法制备Ni2P/Al2O3-ZrO2催化剂。运用X射线衍射、N2吸附-脱附、X射线光电子能谱技术对载体和催化剂进行表征,并以噻吩加氢脱硫、吡啶加氢脱氮反应为探针考察复合氧化物对Ni2P催化剂加氢活性的影响。结果表明,在Al2O3表面引入少量ZrO2,既保持了γ-Al2O3大比表面积的结构优势,又减少了P或Ni与Al2O3表面的接触,促进Ni2P的形成。载体中ZrO2质量分数20%的Ni2P/Al2O3-ZrO2催化剂活性最高,载体焙烧温度过高会导致催化剂活性下降。 相似文献