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1.
探讨了固体酸H对富马酸与甲醇反应生成富马酸二甲酯(DMF)的催化活性,用正交试验确定了反应条件对DMF收率的影响,确定了合成的最佳工艺条件;反应温度为353K,瓜尖为7h,经剂用量为5%,醇酸摩尔比为5:1,在此反应条件下的收率接近92%,进行了催化剂重复使用华本月率剂对DMF合成具有较好的催化活性及重得使用性。  相似文献   

2.
哌嗪合成中催化剂的研究   总被引:10,自引:1,他引:9  
以N-β-羟乙基乙二胺为原料合成哌嗪,研制出一种高活性和选择性铜/载体型催化剂,并探讨了催化剂组成等因素对反应的影响,在Cu-Cu-Mn/γ-Al2O3催化剂和氢气的存在下,于180℃下反应2h,原则料转化率达98%以上,哌嗪收率为88%。  相似文献   

3.
固定床固体酸催化乙酸/丙烯酯化合成乙酸异丙酯   总被引:8,自引:0,他引:8  
在固定床反应系统中,考察了几种固体酸催化剂对于乙酸/丙烯酯化反应的催化作用,研究了温度、压力、进料空速以及原料中水的含量对催化剂活性的影响。实验发现:对于HD-1催化剂,在130℃、11MPa、乙酸进料空速(LHSV)为252h-1的条件下,乙酸单程转化率可达886%,生成乙酸异丙酯的选择性可达99%,催化剂连续运转100h,活性无明显的变化。  相似文献   

4.
Pd/C及Pd-Bi/C催化剂制备及催化氧化性能研究   总被引:1,自引:0,他引:1  
对Pd/C及Pd-Bi/C催化剂的制备方法及空气氧化葡萄糖制葡萄糖酸钠进行了研究。试验结果表明,Pd-Bi共浸方法制备的催化剂活性最好。在50~55℃、pH9~10、葡萄糖浓度为10%~20%时,使用Pd-Bi/C催化剂反应2.5h转化率为97%,选择性达99%以上;与此相比,使用Pd/C催化剂则需要4.5h才达到此转化率。在反应过程中,发现在反应速率与时间关系中,存在着“振荡”现象,此现象是由于Pd-Bi/C催化剂具有高活性,从而强烈吸咐氧而产生的自身中毒和解毒所造成,本文对此现象进行了理论探讨。  相似文献   

5.
Pd/C及Pd—Bi/C催化剂制备及催化氧化性能研究   总被引:1,自引:0,他引:1  
李光兴  缪建英 《化学试剂》1996,18(4):207-210
对Pd/C及Pd-Bi/C催化剂的制备方法及空气氧化葡萄糖制葡萄糖酸钠进行了研究。试验结果表明,Pd-Bi共浸方法制备的催化剂活性最好。在50 ̄55℃、pH9 ̄10、葡萄糖浓度为10% ̄20%时,使用Pd-Bi/C催化剂反应2.5h转化率为97%,选择性达99%以上;与此相比,使用Pd/C催化剂则需要4.5h才达到此转化率。在反应过程中,发现在反应速率与时间关系中,存在着“振荡”现象,此现象是由于  相似文献   

6.
甲苯氧化甲基化制苯乙烯双碱金属/La2O3催化剂   总被引:2,自引:0,他引:2  
在常压固定床流态化反应装置上,考察了双碱金属促进的La2O3催化剂在甲苯氧化基化反应中的催化活性、选择性。结果表明:双碱、钾促进的La2O3体系是良好的甲苯氧化甲基化制苯乙烯催化剂。其中用质量分数各为7%的NaOH、KOH促进的La2O3催化体系,在反应温度为750℃,空速为13.7L/(g.h)、原料报分压C7H8:CH4:O2:N2=1:11.2:2.1:10.4条件下,甲苯单程转化率为46.  相似文献   

7.
糠醛气相加氢制糠醇催化剂的研制   总被引:7,自引:1,他引:6  
用溶胶凝胶法制得糠醛加氢制糠醇的Cu-Zn-Al-A催化剂,研究了制备条件对催化剂性能的影响,并对催化剂进行了TPR、BET、XRD等表征。该催化剂活性评价结果表明,在常压、反应温度130℃、糠醛进料量为2ml/h和氢醛摩尔比为9∶1的条件下,糠醛转化率为99.8%,糠醇选择性为97.77%。  相似文献   

8.
蒋先明  蒙贵愫 《化学试剂》1994,16(6):341-344
究了KCIO3/糠醛及V2O5/MoO3摩尔比,反应温度,反应体系酸度,相转移催化剂,反应时间等因素对糠醛液相氧化合成富马酸的影响。实验证明反应温度,反应体系的酸度,TEBAC相转移催化剂用量是影响富马酸收率的主要因素。找出了最佳反应条件。富马酸收率82.9%,高于文献报道的最高收率(82.18%),反应时间从文献报道的10h缩短到2h。  相似文献   

9.
进行了Ag/ZSM-5/SiO2催化氧化乙醇制乙醛的扩大实验。结果表明,该催化剂有较高的催化活性,在340℃,空速为1640h-1时,乙醇转化率为91.4%,乙醛选择性为99.3%,而且其稳定性也较好。  相似文献   

10.
本文报道用于甲基丙烯醛(MAL)选择氧化制甲基丙烯酸(MAA)的PMoV杂多酸盐催化剂的研究结果。IR和XRD考察结果表明,本文所研究的催化剂均具有稳定的Keggin结构,催化剂物相组成为H(4-2y-2)PO4(MoO3)(12-x)(VO3)xCUyCsz。在300℃,原料气组成MAL:H2O:O2:N2=1:10:3:32.体积空速1200h(-1)的条件下,最佳催化剂的MAL转化率为94.1%,MAA选择性达88.7%。  相似文献   

11.
气相直接法甲醇氧化羰化合成碳酸二甲酯催化剂的研究   总被引:7,自引:0,他引:7  
采用气相直接法甲醇氧化羰化工艺路线合成碳酸二甲酯,以CuCl2为活性组分,用浸渍法制备催化剂。比较了活性炭等数种载体,并对载体进行表面改性,考察了催化剂制备过程中溶剂、助剂、同液比、浸渍浓度与次数、浸渍时间等因素对催化剂性能的影响  相似文献   

12.
倪邦庆  贾国亮  范明明  王辉 《化工进展》2013,32(2):359-363,380
以葡萄糖为原料制备了碳基固体酸催化剂,利用碳酸二甲酯(DMC)与正丙醇的酯交换反应为探针反应,考察了制备条件对碳基固体酸催化活性的影响。结果表明,在碳化温度350 ℃、碳化时间2 h、磺化温度130 ℃、磺化时间10 h、浓硫酸与碳材料的质量比为100∶1的条件下,制备的固体酸具有较好的催化活性;当n(丙醇)∶n(DMC)=2∶1、反应温度90 ℃、反应时间5 h、催化剂用量占原料总质量4%时,碳酸甲丙酯(MPC)选择性超过90%,收率达到40%左右。催化剂催化活性较稳定,连续催化反应4次活性没有明显下降。  相似文献   

13.
The two-step synthesis of diphenyl carbonate (DPC) from dimethyl carbonate (DMC) and phenol has been compared in liquid phase and gas phase, both over heterogeneous catalysts. In the first step, equilibrium yields of methyl phenyl carbonate (MPC) in the transesterification of DMC and phenol were very low at low temperatures in the liquid phase although reaction rates were fast. This endothermic reaction was more favorable at high temperatures in the gas-phase reaction. Titanium oxide catalysts supported on SiO2 or activated carbon were found to be effective in a continuous gas flow reactor. In case of the second step, the disproportionation of MPC, selective formation of DPC was not feasible in the gas-phase reaction due to extensive side reactions. However, there was no by-product in the liquid-phase reaction over the TiO2/SiO2 catalyst. Therefore, our proposed two-step synthesis process consists of the gas-phase transesterification of DMC and phenol followed by the liquid-phase disproportionation of MPC to DPC, both over the TiO2/SiO2 catalyst. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

14.
由CO2合成碳酸二甲酯(DMC)是CO2资源化的重要途径之一。超临界CO2因具有独特的溶解和传递性能,在合成反应中可既作反应物,又作反应溶剂。本实验以超临界CO2、环氧丙烷和甲醇作为反应物,选用金属醋酸盐与K2CO3、KI复合催化一步合成DMC。在温度130~170℃、CO2压力2~14 MPa条件下,考察了催化剂用量、物料配比、温度、压力、反应时间等条件对DMC产率的影响,产物采用气相色谱以内标法进行定量分析。结果表明,当醋酸锌复合催化剂配比为K2CO3:KI:Zn(CH3COO)2=1:1:2时,在合适的反应条件下(催化剂用量4%,物料配比8:1,160℃、7.4MPa,反应4 h),环氧丙烷转化率可达95%,DMC产率可达54.3%。  相似文献   

15.
Excellent yield of dimethyl carbonate (DMC) was obtained by direct physical or chemical adsorption of carbon dioxide on [EmimOH][NTf2] ionic liquid (IL) in the presence of samarium oxychloride (SmOCl) and 1,8-diazabicyclo[2.2.2]undec-7-ene (DBU) as a super base. The novel ternary catalyst system consisting of [EmimOH][NTf2], DBU, and SmOCl was found to appreciably convert methanol (13.01%) to DMC with excellent selectivity (99.13%). The adsorption of CO2 on IL in the presence of DBU was analyzed by 13C experiment. Moreover, catalytic reactivity of SmOCl and OH-functional group was proved by a predictable mechanism. Various parameters such as reaction temperature, pressure, reaction time, and reusability of catalyst were investigated to maximize DMC yield.  相似文献   

16.
The 0.4 nm molecular sieve supported Cu-Ni bimetal catalysts for direct synthesis of dimethyl carbonate (DMC) from CO 2 and CH 3 OH were prepared and investigated. The synthesized catalysts were fully characterized by BET, XRD (X-ray diffraction), TPR (temperature programmed reduction), IR (infra-red adsorption), NH 3-TPD (temperature programmed desorption) and CO 2-TPD (temperature programmed desorption) techniques. The results showed that the surface area of catalysts decreased with increasing metal content, and the metals as well as Cu-Ni alloy co-existed on the reduced catalyst surface. There existed interaction between metal and carrier, and moreover, metal particles affected obviously the acidity and basicity of carrier. The large amount of basic sites facilitated the activation of methanol to methoxyl species and their subsequent reaction with activated carbon dioxide. The catalysts were evaluated in a continuous tubular fixed-bed micro-gaseous reactor and the catalyst with bimetal loading of 20% (by mass) had best catalytic activities. Under the conditions of 393 K, 1.1 MPa, 5 h and gas space velocity of 510 h 1 , the selectivity and yield of DMC were higher than 86.0 % and 5.0 %, respectively.  相似文献   

17.
Polymerizations of propylene oxide (PO) have been carried out by using double metal cyanide (DMC) catalyst prepared by reacting ZnCl2 and K3[Co(CN)6] in the presence of tert-butyl alcohol as a complexing agents. The DMC catalyst of the molecular formula, Zn2.3Cl1.0[Co(CN)6]1.0·2.0 tBuOH·1.0H2O, is characterized by gas sorption measurements, infrared spectroscopy and X-ray powder diffraction. The structure of DMC catalyst with negligible surface area and broadened X-ray diffraction peaks is different from that of Prussian blue analogue, Zn3[Co(CN)6]2·12H2O of microporous crystalline materials. The PO polymerization behavior is tunable by combining it with various imidazolium based ionic liquids (ILs) as external additives. Thus, (1) they make the zinc-monomer bond faster activated during the initial stage of polymerization, (2) they make the zinc-monomer bond more active, (3) they stabilize the polymerization centers and prevent their decomposition, and (4) they improve important polymer properties such as molecular weight, viscosity and unsaturation level. The maximum rate of polymerization (Rp,max) of DMC catalyst increases from 2587 to 27,222 g-polymer/g-cat h by combining with 1-ethyl-3-methylimidazolium chloride (emimCl, [emimCl]/[Zn] = 1.25) at 115 °C. The induction period as the time to reach Rp,max becomes short from 321 min for DMC catalyst to 29 min for DMC/emimCl binary catalyst. The unsaturation value of polyol (0.017 mequiv./g) produced by DMC decreases to 0.005 mequiv./g by simply combining with IL. The molecular weight polyol produced by DMC catalyst increases from Mn = 3700 to more than 6000, and the viscosity of polyol decreases by combining with ILs.  相似文献   

18.
张鹏  刘定华 《化工进展》2016,35(7):2081-2090
针对CO2与环氧烷烃共聚制备脂肪族聚碳酸酯反应体系,本文在综合分析脂肪族聚碳酸酯应用前景的基础上,着重介绍了双金属氰化络合催化剂在该工艺中的研究进展,并对不同种类活性中心金属的组合在不同反应体系中的催化效果进行了分析。共沉淀法制得的Zn-Co双金属氰化络合催化剂在CO2与环氧烷烃的催化体系中,通过改变制备方法、配体等条件可以实现对催化剂形貌的控制,有利于催化活性的提升。Zn-Fe双金属氰化络合催化剂对于环氧丙烷开环活性较好。同时还介绍了采用其他活性中心金属组合制得的双金属氰化络合催化剂,发现对于CO2与环氧烷烃共聚活性受中心金属及配体的影响较大。最后,对该共聚反应的机理进行了分析,为双金属氰化络合催化剂的设计研究指明了方向。  相似文献   

19.
制备了钴锌双金属氰化物/戊二酸锌复合催化剂(DMC/ZnGA),研究了催化剂的组成对CO2与环氧丙烷共聚反应的影响;采用凝胶渗透色谱、核磁共振谱、红外光谱和热重分析对共聚产物进行了表征,结果表明,钴锌双金属氰化物/戊二酸锌复合催化剂表现出明显的协同效应,能高效催化CO2与环氧丙烷的共聚反应,共聚产物的数均分子量在18 000~31 000;通过调节催化剂的配比,最高催化效率达到168 g-聚合物·(g-催化剂)-1,反应生成共聚产物的反应选择性大于97%。  相似文献   

20.
Zn3 [Co(CN)6]2 based double metal cyanide complex(Co-Zn DMC) is synthesized and characterized by element analysis, FT-IR, TG-FTIR, XRD and TEM. The composition of Co-Zn DMC summarized by elemental analysis has been confirmed by TG-FTIR. The catalyst has high crystallinity according to strong crystalline peaks shown in XRD and diffraction spot observed by TEM. Copolymerization of epoxides and carbon dioxide are successfully catalyzed by Co-Zn DMC. The efficiency of catalysts is as high as 7488 g polymer/g catalyst for CO2/propylene oxide (PO), 1100 g polymer/g catalyst for CO2/ethylene oxide (EO), which are higher than that reported ever before. The effects of various reaction conditions such as amount of the catalyst, reaction time and temperature on the copolymerization are investigated. The results show that insertion of CO2 into chains is significantly affected by the catalyst quantity and ambient temperature. The weight percentage of byproduct cyclic carbonate can be easily controlled to be less than 5% while the molar fraction of CO2 in backbone (fco2) is more than 30%.  相似文献   

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