共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
3.
丁烯在HZSM-5分子筛催化剂上发生齐聚、裂化等反应。本文在等温固定床反应器中以HZSM-5分子筛为催化剂,考察并研究了空时、温度和分压等反应条件对丁烯齐聚反应以及高碳烯烃进一步裂化反应的影响。实验结果表明,增大空时可提高丁烯转化率,但会加剧高碳烯烃的进一步裂化反应并导致C8的选择性降低;为提高高碳烯烃的选择性,空时不应过高;当空时为0.17kg·s/mol和0.50kg·s/mol时,随温度(220~410℃)的升高丁烯转化率先增大后减少,在300℃时转化率达到最大值。对此实验现象本文中结合丁烯消耗速率方程做出了解释。高温条件下高碳烯烃进一步裂化生成低碳烯烃,因此低温则有利于齐聚反应生成高碳烯烃;提高分压增大丁烯消耗反应速率,有利于齐聚反应生成高碳烯烃,反应速率与分压有线性关系。 相似文献
4.
5.
6.
顺丁烯二酸二甲酯合成反应宏观动力学研究 总被引:14,自引:0,他引:14
利用固定床积分反应器考察了反应温度、空速对顺酐与甲醇反应生成顺丁烯二酸二甲酯反应的影响,并对实验数据进行回归,得到了宏观动力学方程式。在实验条件范围内,甲醇与顺酐酯化生成单酯的反应可以看成不可逆反应;甲醇与单酯进一步反应生成双酯的反应为可逆反应;甲醇过量条件下甲醇与顺酐酯化反应中甲醇的反应级数为0级。 相似文献
7.
采用密度泛函理论(DFT),对碳酸二苯酯(DPC)的不同合成反应路径进行了热力学分析。首先优化了反应中涉及的各种物质在气体状态下的稳定结构,在此基础上计算了各物质液体状态下的热力学性质,获得了碳酸二甲酯-苯酚(DMC-Ph OH),碳酸二甲酯-乙酸苯酯(DMC-PA)两种不同酯交换反应路径的焓变、熵变、吉布斯自由能变以及平衡常数。计算结果表明,两种合成反应均为吸热反应;从热力学角度来看,DMC-PA反应路径优于DMC-Ph OH反应路径,其反应平衡常数更大,利于DPC的生成。但两种合成路径各步反应的平衡常数KC均偏小,为提高DPC收率,需要在反应进行过程中,不断移走产物以打破热力学平衡限制。同时,从热力学角度分析,若DMC同Ph OH的反应采用"两步法",DMC同PA的反应采用"一步法",则较有利于DPC的生成。 相似文献
8.
以大豆油与环氧化剂反应,生成环氧大豆油;在催化剂的存在下与含活泼氢的亲核试剂发生环氧键开环反应,生成混合羟基脂肪酸甘油酯;加入醇并升温进行醇解反应,生成混合羟基脂肪酸单酯,即大豆油基多元醇。将大豆油基多元醇与异氰酸酯(MDI)等反应即可制得硬质聚氨酯泡沫塑料,具体配方为100份大豆油基多元醇,80~150份MDI、0.3~4份三乙醇胺、0.5~4份匀泡剂、0.5~3份蒸馏水。 相似文献
9.
10.
金属氯化物对亚临界水中纤维素水解反应的影响 总被引:4,自引:0,他引:4
研究了纤维素在亚临界水中无催化水解及分别添加ZnCl2、FeCl3、CuCl2、AlCl3对水解反应的影响。实验结果显示,无催化剂时,葡萄糖的收率在280℃,60s及(7.0±0.2)MPa时达到最大为14.3%。添加ZnCl2、FeCl3、CuCl2及AlCl3均能促进纤维素的水解及葡萄糖的降解。纤维素的水解及葡萄糖的降解反应级数均为一级。利用一级反应模型对纤维素在260℃水解及葡萄糖的降解反应进行数据拟合,求得了纤维素的水解速率常数(k),葡萄糖的生成速率常数(k1)及葡萄糖的降解速率常数(k2)。添加AlCl3体系中纤维素的水解速率常数(k)大于葡萄糖的降解速率常数(k2),有利于葡萄糖的生成,在260℃,120s及(5.2±0.2)MPa时,葡萄糖收率达到最大为46.05%。添加ZnCl2、CuCl2及FeCl3体系中葡萄糖的降解速率常数(k2)大于纤维素的水解速率常数(k),不利于葡萄糖的生成。XRD分析显示,金属氯化物的加入并没有破坏纤维素的晶体类型,水解残渣仍然保持纤维素Ⅰ型晶体结构。 相似文献
11.
Jianguo Liu Yizan Zuo Minghan Han Zhanwen Wang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(3):408-414
BACKGROUND: Loss of the active CuCl component occurs during acetylene dimerisation to monovinylacetylene (MVA) catalysed by an anhydrous catalyst with the formation of a dark red precipitate. Acidic species can reduce the loss of CuCl but have an unfavorable influence on acetylene dimerisation. This study aims to determine the precipitate composition and regulate the acidity of the catalyst to find a balance between reaction rate, MVA selectivity and catalyst life. RESULT: The precipitate composition was 2CuCl·3C2H2·1/3CH3CH2NH2·1/7C3H7NO, formed by the combination of DMF, CH3CH2NH2, C2H2 and the [Cu]‐acetylene π‐complex, which is an intermediate in the reaction. From an overall consideration of the loss of CuCl, conversion of acetylene, and selectivity of MVA, the reaction temperature and acetylene space velocity were optimized at 65 °C and 200 h?1, respectively. The introduction of HCl into the catalyst with a rate of 3.2 h?1 could reduce CuCl loss by 73.5%, whereas conversion of acetylene was only lowered by 9.0%. CONCLUSION: Acidity regulation of the anhydrous catalyst by optimising the reaction temperature, acetylene space velocity, and rate of addition of HCl shows little negative effect on acetylene conversion and selectivity to MVA but can reduce CuCl loss significantly. © 2012 Society of Chemical Industry 相似文献
12.
13.
传统催化剂催化甲醇氧化羰基化合成碳酸二甲酯(DMC)因氯离子的存在易导致腐蚀、失活,通过负载、添加助剂或配体的铜催化体系可改善上述问题。本文介绍了各改进催化体系,并综述了其反应机理。其中负载CuCl2或CuCl催化剂的活性中间体是Cu(OCH3)Cl或Cu2(OH)3Cl;亚铜与配体混合时,配体的种类、数量、结构等会影响甲氧基铜物种的形成;固体离子交换得到的Cu-分子筛催化剂实现了无氯化,然而活性较低;将Si、Al、Ti等氧化物作为载体时,对载体表面结构的改性改善了催化性能。大多数铜催化体系的控制步骤为CO对甲氧基铜物种的插入反应,然而对于甲氧基铜物种的产生以及CO对甲氧基铜物种插入后的产物仍存在分歧。指出进一步研究各催化体系的反应机理仍然是今后工作的重点。 相似文献
14.
用新型的具有恒定温度环境的反应热量计,以一定比例的4 m ol· L- 1 H Cl与无水乙醇混合溶液作为量热溶剂,分别测定了反应物和产物的溶解焓,设计了一个新的热化学循环,得到了固相配位反应的反应焓△r Hθm = 54.780 k J·m ol- 1,估算了配合物 Cu Cl2·( C7 H9 N)2 标准生成焓△f Hθm = - 348.802 k J·m ol- 1。 相似文献
15.
16.
介绍了气相直接法和气相间接法的工艺特点,比较了各类活性催化剂的结构特征及其催化性能。分析认为,气相间接法的关键是有效控制第一步反应并确保剧毒NO气体的安全循环使用;气相直接法避免了NO有毒气体的使用。评述了固态离子交换法制备的铜分子筛在气相直接法合成DMC反应中表现出比负载型CuCl2催化剂和Wacker型催化剂更高的稳定性以及较低的腐蚀性,但受分子筛表面酸位的限制,存在交换容量低,残余CuCl难以脱除的不足;而浸渍法制备的无Cl型铜分子筛对DMC的选择性较低;硅基复合氧化物通过改变制备条件可以有效控制表面B酸位的数量、强度及其分布,是基于固态离子交换反应原理制备负载铜催化剂的理想载体材料,值得关注。 相似文献
17.
The conventional thermal Sonogashira C C coupling reaction requires the use of a palladium catalyst and a large amount of ligands. Although there were a few reports describing the use of inexpensive metal catalysts, such as, copper (Cu), iron (Fe), and nickel (Ni), for replacement of palladium (Pd) in the Sonogashira reactions, it was later questioned that the observed effects were due to ppb levels contamination of Pd present in the reagents used in the reactions. Herein, we report that simple copper(I) chloride (CuCl) salt, in the absence of Pd and ligands, can catalyze the Sonogashira reaction with high yields (80–99%) under blue LED light irradiation at room temperature. Control experiments show that no cross‐coupling product was formed, when palladium(II) chloride (PdCl2) was used to replace CuCl as a catalyst. A series of electron‐rich and electron‐poor substituted aryl halides (bromides and iodides) as well as aryl‐ and alkylacetylenes are examined and the reaction mechanism is discussed. 相似文献
18.
A bi-component catalyst comprising CuC1 and metallic copper was used in the direct synthesis of me- thylchlorosilane to study the catalytic synergy between the different copper sources. The catalyst exhibited high ac- tivity and high selectivity of dimethyldichlorosilane (M2) in the stirred bed reactor. The effect of the proportion of CuC1 used was studied and 10%-30% CuC1 gave the best yield of M2. The use of CuC1 decreased the induction pe- riod of reaction, improved the selectivity in the induction stage, and gave a longer stable stage. These results sug- gest that bi-comoonent catalyst has advantazes in the direct synthesis reaction. 相似文献
19.
20.
A. L. Ashkalunin E. S. Derkacheva V. I. Leiman I. I. Osovskaya N. A. Gerasin 《Glass Physics and Chemistry》2017,43(4):319-325
The details of the formation of CuCl nanoparticles in the sodium alumina-borosilicate glass for different methods of thermal treatment of the samples are studied by exciton thermal analysis. It is revealed that the formation of the CuCl phase in glass depends on the heating rate of the samples to the predetermined temperature of isothermal annealing. The concentration of the nucleating centers of the CuCl phase reaches its peak value at 600°C during slow (60 min) heating up to 650°C, due to the fast increase of the critical size of particles of the phase as a result of the fast temperature increase and the rapid decrease of supersaturation in glass. As a result, the formation of new CuCl nucleation centers terminates above 600°C, and part of the centers formed earlier whose size is less than critical dissolve, which results in the monotonic decrease of the CuCl particle concentration. 相似文献