共查询到16条相似文献,搜索用时 109 毫秒
1.
2.
以B2O3为助催化剂,采用研磨混合法改性Na2CO3催化剂,在固定床反应器中催化甲醇脱氢制备无水甲醛,考察催化剂的组成和反应条件等对催化反应的影响,采用XRD、TG-DTG、N2吸附-脱附、SEM和CO2-TPD等对催化剂进行表征。结果表明,以B2O3为助催化剂采用机械研磨混合法改性的Na2CO3催化剂,增加了催化剂的比表面积,在(10~30) nm增加了大量的孔道,平均孔径达18.44 nm,比表面积为1.65 m2·g-1,且B2O3分布均匀,改性后的催化剂碱性降低,在催化甲醇脱氢制备无水甲醛的反应中,催化活性明显高于Na2CO3催化剂,表明B2O3改性Na2CO3催化剂能提高甲醇转化率和甲醛选择性。在B2O3/Na2CO3催化剂中B2O3质量分数为30%、甲醇进料质量分数为26%、反应温度为650 ℃和甲醇重时空速为2.94 h-1条件下,甲醇转化率达59.97%,甲醛选择性达83.28%。 相似文献
3.
0前言
甲醛是化学工业中的一种重要的大宗产品,由于它具有较强的反应性,所以甲醛非常广泛地用于如薄膜的研究开发、纺织工业和皮革工业,用作杀菌剂、或在无碳复写纸的生产中用作黑墨汁母体的微囊包封过程中的鞣剂。不过,生产的甲醛大部份用于各种树指和塑料的制取。 相似文献
4.
利用甲醇催化脱氢合成无水甲醛是一条新的工艺路线。评述了这一领域内的研究进展,所研究的催化剂有四大类,其中一些有较高的甲醇转化率和甲醛的选择性。 相似文献
5.
7.
8.
9.
分别制备了以Mn、Ce、Cu、Zn、K等为助剂的Cr/SiO2催化剂,考察了助剂在逆水煤气变换耦合乙烷脱氢制乙烯反应中对Cr/SiO2催化剂反应性能的影响。结果表明,高温下Mn的加入有利于催化活性的提高,Cr-Mn/SiO2催化剂显示了较好的催化活性。在740℃、n(CO2)/n(C2H6)=7的条件下,乙烷转化率为47%,乙烯选择性为99%。XRD、XPS、UV-DRS和TPR技术的表征表明催化剂表面存在Cr3+、Cr6+、Mn4+物种,Mn的加入使得催化剂还原性能增强,有助于反应过程中氧化还原循环的进行,提高了反应活性。 相似文献
10.
11.
Kwang-Deog Jung Oh-Shim Joo Sung-Hwan Han Sung-Jin Uhm In-Jae Chung 《Catalysis Letters》1995,35(3-4):303-311
The deactivation of Cu/ZnO catalyst during methanol dehydrogenation to form methyl formate has been studied. The Cu/ZnO catalyst was seriously deactivated under the reaction conditions: various temperatures of 493, 523 and 553 K, atmospheric pressure and methanol GHSV of 3000 ml (STP)/g-cat h. The weight loss due to reduction of ZnO in the Cu/ ZnO catalyst was monitored by a microbalance. X-ray induced Auger spectroscopy of Zn(L3M4,5M4,5) showed the increase in the concentration of metallic Zn on the catalyst surface after the reaction. Temperature-programmed reduction (TPR) of the Cu/ZnO catalyst with methanol demonstrated that the reduction of ZnO in Cu/ ZnO was suppressed by introduction of CO2 into the stream of helium-methanol. As the concentration of CO2 in the feed gas increased, the weight loss of the Cu/ZnO catalyst due to the reduction of ZnO decreased. The deactivation of the Cu/ZnO catalyst in the methanol dehydrogenation was also retarded by the addition of CO2. In particular, oxygen injection into the reactant feed regenerated the Cu/ ZnO catalyst deactivated during the reaction. Based on these observations, the cause of deactivation of the Cu/ZnO catalyst has been discussed. 相似文献
12.
甲醛与乙炔发生炔化反应合成1,4-丁炔二醇,选用铜铋作为催化剂。模拟最具代表性的工业炔化催化剂以研究甲醛乙炔化反应的活化过程,制备高性能CuO-Bi2O3/SiO2-MgO催化剂,结合XRD、H2-TPR、TG-DTA和N2-TPD-MS等表征,研究炔化催化剂活化过程中铜物种的转变,获得最优催化剂活化方法。结果表明,CuO在甲醛溶液中无乙炔存在下可定向转化为Cu2O,但经乙炔活化后活性较低,归因于还原过程中Cu物种的流失及晶粒长大。而在甲醛与乙炔协同作用下,CuO可快速转变为Cu的炔化物种,表现出较高的炔化活性。表明炔化催化剂的活化过程必须在甲醛与乙炔同时存在的条件下进行。 相似文献
13.
C.H. Rochester 《Catalysis Letters》1998,52(1-2):121-121
This note rectifies serious omissions from the references included in a recent paper by Fujitani et al. concerned with methanol
synthesis over Cu/SiO2 containing ZnO.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
Ching-Yeh Shiau J. C. Tsai 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1998,73(4):414-420
Cu/SiO2 catalysts prepared by an electroless deposition method were investigated and compared with those by an impregnation method. Copper contents varied from 5% to 15% and SiO2 was used as support. All catalysts were characterized by BET, DSC, SEM and TPR and tested by an n-butanol dehydrogenation reaction for activities and stabilities. BET analysis showed that the catalysts prepared by the two methods present larger average pore size and less surface area than those of the fresh SiO2, indicating that smaller pores may get blocked during the course of preparation. This blockage is more severe in the impregnation method. SEM photos showed that the electroless method produces smaller copper crystals than the impregnated method. The reaction activity was found to be in the order of the calcined electroless copper catalyst>the fresh electroless copper catalyst>impregnated copper catalyst. © 1998 Society of Chemical Industry 相似文献
15.
甲醇氧化制甲醛铁钼催化剂研究 总被引:1,自引:0,他引:1
采用共沉淀法制备了不同Mo与Fe原子比的甲醇氧化制甲醛催化剂,在常压固定床反应器上对催化剂进行活性评价,采用BET、XRD和TEM对制备的催化剂进行表征。结果表明, Mo与Fe原子比为2.2~2.8时,催化剂具有较好的活性,(400~450) ℃焙烧的催化剂具有良好的比表面积、适宜的孔容和孔径,形成了较为稳定的MoO3和Fe2(MoO4)3晶相,使催化剂具有更高的活性和选择性。对甲醇氧化制甲醛反应进行研究,结果表明,在反应温度(265~315) ℃,空速(8 500~13 000) h-1时,甲醇转化率>98%,甲醛收率>93%, 500 h长周期考核,催化剂表现出良好的活性和稳定性。 相似文献
16.
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