载体改性与助剂对低金乙炔氢氯化无汞催化剂性能的研究

发布时间：2018-05-05 23:03

本文选题：乙炔氢氯化反应 + 表观活化能　；参考：《内蒙古大学》2017年硕士论文

【摘要】：本论文主要研究低含量Au基催化剂,含量为0.25%,作为活性组分,采用载体改性和加入助剂两个方面对用于乙炔氢氯化反应催化剂性能的研究,采用N2物理吸附,XPS,H2-TPR,C2H2-TPD,TG,TEM和SEM等多种手段对新鲜的和反应后的催化剂样品的物相组成、结构性质、氧化还原性能、对反应物气体HC1和C2H2的吸附能力进行对比分析,探索了载体改性和添加助剂后对于低含量的Au基负载型催化剂的催化性能的影响,得出如下结论。1.采用浸渍法制备了系列硼改性的低含量Au C0.25wt.%)基催化剂并在乙炔氢氯化反应中测试其催化性能并对硼(B)改性前后的催化剂的性能进行对比分析,活性测试结果表明通过硼(B)改性后催化剂与未改性催化剂相比,在空速为770h-1,温度为150℃反应条件下,乙炔转化率提高21.4%,氯乙烯的选择性提高2%左右;结果表明加入硼(B)物种可以形成B-C-0键,从而降低了 Au3+的电子云密度,抑制Au3+→Au0的还原;加入硼(B)物种可以明显降低催化剂在反应过程中的积碳量,从而提高了催化剂的稳定性;发现反应后的硼(B)改性与未改性催化剂相比,反应后的硼(B)改性催化剂的Au纳米粒子粒径较小,催化剂的活性较高,表明小纳米粒子Au有助于乙炔氢氯化反应;乙炔的吸附能力并不是影响催化剂稳定性和催化剂的活性的主要原因,然而催化剂对氯化氢的吸附能力是影响催化剂的稳定性和活性的主要原因;加入硼(B)后可以显著的提高催化剂样品对HC1气体的吸附能力,从而增强了催化剂的稳定性。2.采用B和N对活性炭载体进行修饰,采用浸渍法制备了系列B和N修饰的Au 0.25%/AC催化,研究了不同比例的B和N修饰的催化剂样品对乙炔氢氯化反应的影响,结果显示采用B和N双修饰活性炭载体后用于乙炔氢氯化反应时,乙炔的转化率可以达到83.5%,与未掺杂样品相比,乙炔的转化率提高了 22.5%,比单独的B修饰催化剂样品提高了 1.6%左右,得出N物种的存在形式对催化剂性能影响较大,总的来说,N物种对催化剂性能的影响大小顺序为N物种的活性顺序为砒啶类型N叽咯类型N四类型N。3.采用浸渍法制备了系列钽(Ta)含量的Au 0.25%X Ta/AC(X=1、3、5、7)双金属催化剂以及Au 0.25%/AC单Au催化剂对乙炔氢氯化反应的影响,筛选出最好的Au0.25%-5Ta/AC双金属催化剂,乙炔的转化率可以达到85.8%,氯乙烯的选择性可以达到99%以上,通过N2物理吸附,XPS,H2-TPR,TG和TEM.等各种表征手段,发现加入Ta后活性组分Au和Ta物种之间存在明显的相互作用,造成Au3+物种的还有峰向高温偏移,使得Au3+物种更难被还原,从而提高了催化剂的稳定性,继续增加Ta物种的含量发现催化活性有所降低,由于加入金属Ta物种的量过多,导致催化剂样品的比表面积的下降,从而降低了催化剂的活性。4.采用浸渍法制备了加入稀土(Ce)助剂后,与活性组分Au组成的Au-Ce双金属催化剂,结果发现当Au的含量为0.25%,Ce的含量为7%时,Au 0.25%-7Ce/AC催化剂表现出了良好的催化活性,在空速为770 h-1，，原料气氯化氢和乙炔的比例为1:1.15,反应温度为150℃时,乙炔的转化率可以达到78%,比单组分Au0.25%/AC催化剂乙炔的转化率高了 17%左右,.同时研究了 Au 0.25%/AC催化剂用于乙炔氢氯化反应时,选择性较低,采用计算和实验的方法,我们认为造成Au 0.25%/AC催化剂用于乙炔氢氯化反应氯乙烯的选择性较低的可能是生成了副产物1,2-二氯乙烷。并且得出加入稀土助剂Ce后可以增大活性组分Au3+物种的电子云密度,从而使得活性组分Au3+物种更加稳定,难被还原,从而增强了催化剂的稳定性。
[Abstract]:This paper mainly studies the low content Au based catalyst, the content is 0.25%. As the active component, the performance of the catalyst used in acetylene hydrogen chlorination is studied by using the carrier modification and adding additives in two aspects. A variety of methods, such as N2 physical adsorption, XPS, H2-TPR, C2H2-TPD, TG, TEM and SEM, are used for the phase of the fresh and reacted catalyst samples. The composition, structural properties, redox properties, the adsorption capacity of the reactant gas HC1 and C2H2 were compared, and the effect of carrier modification and additive on the catalytic performance of the low content Au based supported catalyst was explored. The following conclusion was drawn that.1. was prepared by the impregnation method for the low content Au C0.25wt.% of series boron modification. The catalytic performance of the catalyst was tested in acetylene hydrogen chlorination and the performance of the catalyst before and after boron (B) modification was compared. The activity test results showed that the conversion rate of acetylene increased by 21.4% and the selection of chloroethylene was 21.4% at the air velocity of 770h-1 and the reaction temperature of 150 C after the modification of boron (B). The result shows that the sex increases about 2%; the results show that the addition of boron (B) species can form the B-C-0 bond, thus reducing the electron cloud density of Au3+ and inhibiting the reduction of Au3+ to Au0. The addition of boron (B) species can obviously reduce the amount of carbon deposition of the catalyst in the reaction process, thus improving the stability of the catalyst, and the modification of the boron (B) and the unmodified catalyst after the reaction is found. Compared, the Au nanoparticles with boron (B) modified catalyst after reaction are smaller in particle size and higher in the activity of the catalyst. It shows that the small nanoparticles Au is helpful to acetylene hydrochlorination, and the adsorption capacity of acetylene is not the main reason for the stability of the catalyst and the activity of the catalyst. However, the adsorption capacity of the catalyst on the hydrogen chloride is influenced by catalysis. The main reason for the stability and activity of the agent is that adding boron (B) can significantly improve the adsorption capacity of the catalyst samples to HC1 gas, thus enhancing the stability of the catalyst.2. by modifying the active carbon carrier by B and N, and using the impregnation method to prepare the Au 0.25%/AC catalysis of a series of B and N modified Au, and study the B and N modification of different proportions. The effect of catalyst samples on acetylene hydrogen chlorination shows that the conversion of acetylene can reach 83.5% when B and N double modified activated carbon carriers are used for acetylene hydrogen chlorination. Compared with the undoped samples, the conversion rate of acetylene is increased by 22.5%, which is about 1.6% higher than that of the single B trimming catalyst, and the N species can be obtained. The existence form has great influence on the performance of the catalyst. In general, the order of the effect of N species on the performance of the catalyst is that the order of the activity of N species is arsenidine type N Serge type N four type N.3., and the Au 0.25%X Ta/AC (X=1,3,5,7) bimetallic catalyst for a series of tantalum (Ta) content is prepared by impregnation method, and the Au 0.25%/AC single catalyst is used for acetylene. The best Au0.25%-5Ta/AC bimetallic catalyst was screened by the effect of hydrogen chlorination. The conversion rate of acetylene could reach 85.8% and the selectivity of vinyl chloride reached over 99%. Through the physical adsorption of N2, XPS, H2-TPR, TG and TEM., it was found that there was an obvious interaction between Au and Ta species after the addition of Ta. The migration of the Au3+ species to the high temperature makes the Au3+ species more difficult to be reduced, thus improving the stability of the catalyst, increasing the content of the Ta species and reducing the catalytic activity. As the amount of the metal Ta species is too much, the specific surface area of the catalyst is reduced, thus reducing the activity.4. of the catalyst. The Au-Ce bimetallic catalyst consisting of the active component Au after adding the rare earth (Ce) additive was prepared. The results showed that when the content of Au was 0.25% and the content of Ce was 7%, the Au 0.25%-7Ce/AC catalyst showed good catalytic activity, at the air velocity of 770 H-1, the proportion of hydrogen chloride and acetylene in the raw gas was 1:1.15, and the reaction temperature was 150 C. The conversion rate of acetylene can reach 78%, which is about 17% higher than that of the single component Au0.25%/AC catalyst acetylene conversion. At the same time, the selectivity of Au 0.25%/AC catalyst in acetylene hydrogen chlorination is low, and the method of calculation and experiment is adopted. We think that the choice of Au 0.25%/AC catalyst for acetylene hydrogen chlorination of ethylene chloride 1,2- two chloroethane, a by-product, was produced, and the addition of rare earth additive Ce could increase the electron cloud density of the active component Au3+ species, thus making the active component of the Au3+ species more stable and difficult to be reduced, thus enhancing the stability of the catalyst.

【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

【参考文献】