对苯二甲酸加氢精制钯/炭催化剂的制备

选取椰壳活性炭为载体制备钯／炭催化剂，考察了浸渍液pH值和还原温度对催化剂结构和活性的影响。用XRD对催化剂进行表征，用对苯二甲酸加氢精制体系进行活性评价。结果表明：催化剂的制备条件对载体炭孔结构影响不明显，金属钯较好的分散在载体炭上；最佳浸渍溶液pH值为1.5，还原温度为250℃。     

加氢精制催化剂活性影响因素的研究进展

介绍了载体、助剂和催化剂的制备方法等因素对催化剂活性的影响,尤其是浸渍法的制备条件包括浸渍顺序、浸渍液浓度、浸渍液初始pH值等因素对催化剂活性的影响,为开发高活性的加氢精制催化剂提供了重要的信息.     

制备条件对Pd-BaO/δ,θ-Al2O3催化蒽醌氢化制备过氧化氢性能的影响

研究了浸渍条件和还原剂种类对蒽醌氢化制备过氧化氢Pd-BaO/δ,θ-Al₂O₃催化剂性能的影响。结果表明,当浸渍液温度60 ℃和pH＝3.5时,催化剂上钯金属的分散度较高,钯粒子较小,催化剂活性较高。使用不同还原剂也会影响催化剂的Pd分散度和粒子大小,其中,以水合肼和H₂还原得到的催化剂有较高的活性比表面积、分散度和较小的粒子尺寸,而经硼氢化钾还原的催化剂的分散度偏低。水合肼还原得到的催化剂的活性较高,H₂还原的催化剂活性次之,以硼氢化钾还原的催化剂活性最差。     

脂肪腈加氢制备单烷基二甲基叔胺催化剂的研究

通过对催化剂活性组分的筛选,钯/碳(Pd/C)催化剂对脂肪腈与二甲胺反应制备单烷基二甲基叔胺有良好的选择性。采用浸渍-沉淀法制备出负载型Pd/C催化剂,考察了制备过程中溶液体系的pH值和浸渍时间对Pd/C催化剂性能的影响。结果表明:该溶液体系在pH值7.9和浸渍15 h~18 h的条件下得到的Pd/C催化剂对脂肪腈催化加氢制备单烷基二甲基叔胺有较好的催化性能。     

氯乙烯生产中低汞高效催化剂的试制与应用

聚氯乙烯作为五大通用树脂之一,具有非常广泛的应用,而氯乙烯是生产聚氯乙烯的主要材料,氯乙烯在生产过程中需要使用到汞催化剂。我国汞资源缺乏,而且汞在应用过程中会污染环境、破坏生态平衡,所以需要严格控制。低汞高效催化剂的试制能够降低汞的使用,降低对环境的破坏程度。在试制过程中,催化剂活性会受到诸多方面的影响,比如浸渍方法、制备条件、HgCl_2含量、干燥温度和助剂配比等,于是文章通过实验研究,对这些影响因素进行分析,从而获得具有更高活性的催化剂。实验结果表明,n(HgCl_2):n(CeCl_3):n(KCl)=1:1:1、浸渍时间6h、pH=1、浸渍温度60℃、干燥温度120℃、HgCl_2含量为3g时,低汞高效催化剂具有更好的活性,能够替代高汞催化剂应用于氯乙烯生产中,并且具有很好的应用效果。     

蛋壳型催化剂结构、制备方法及其催化性能影响因素分析

综述了蛋壳型催化剂结构及制备方法,并对蛋壳型催化剂的浸渍制备法和制备过程中的影响因素如溶液浓度、溶剂极性、浸渍时问、溶液pH值和载体等进行了总结和评述.介绍了活性组分呈蛋壳型分布对催化剂性能的影响以及活性组分最优分布状态理论.     

干法水泥生产线用燃煤烟气脱氮催化剂的研究

为了控制NOx我们使用选择性催化还原法(SCR)制作了催化剂,此催化剂是钒掺杂的二氧化硅,负载过程使用了正交试验法。结果表明:载体中经CTAB和KCl处理的载体具有最佳的脱硝性能,负载过程中活性组分含量为8%、偏钒酸铵与草酸铵比为1∶1、浸渍温度为80℃、浸渍时间为4小时,且经过氮化处理的催化剂具有最佳的脱硝性能,180℃条件下脱硝效率可达85.95%,4个因素的极差顺序为:浸渍时间浸渍温度活性组分含量偏钒酸铵与草酸比。     

Co改性的Pd/C催化剂在转移加氢中的应用研究

通过调整Co和Pd的浸渍顺序制备了不同的钴改性的Pd/C催化剂,考察了催化剂在3,5-二羟基苯甲酸转移加氢制备3,5-二氧代环己烷羧酸反应中的活性。确认先浸渍钴后浸渍钯、并在300℃以氢气还原得到的Co-Pd/C催化剂具有最佳活性,反应转化率和选择性分别达到94.6%和99.5%。对该催化剂以BET、TPR、XRD、SEM、TEM、XPS等手段进行了表征。结果表明,先浸渍的钴占据了活性炭的微孔使最可几孔径由2.72nm增大为3.32nm,并且与一些对反应不利的官能团作用,使后浸渍的钯主要分布在催化剂的大孔中,避免了过多深度加氢副产物的生成。催化剂活性组分为零价的钯,其平均粒径约10nm,以有利于转移加氢的聚集态存在,使催化剂获得了较高的活性和选择性。     

关于精对苯二甲酸(PTA)生产用钯碳催化剂的制备研究

本文主要对精对苯二甲酸(PTA)生产用钯碳催化剂的制备与再生进行了分析。首先对新鲜催化剂制备与催化剂活性评价进行了分析,接着对制备过程对催化剂活性的影响进行了分析,主要是吸附周期及还原过程的影响,最后对钯催化剂寿命延长及再生进行了研究,钯碳催化剂寿命延长失活与钯碳催化剂再生能够再生失活钯碳催化剂。     

新型蒽醌加氢催化剂的研制和工业应用

高活性、高选择性催化剂是解决葸醌法生产过氧化氢过程中瓶颈问题的根本途径。研制的新型钯催化剂,活性组分浸渍层薄,催化剂活性高及反应稳定性好,实验室模式评价实验和工业应用表明,研制的新型催化剂表现出良好的活性及选择性,其时空产率超过目前工业用的催化剂。     

模拟印染废水处理中贵金属钯催化剂的研究

选用三叶草状γ-Al2O3为载体,采用等量浸渍法制备了负载型复合催化剂,各组成分比例为:Pd∶Cu∶Fe∶Ce∶La=0.5∶0.5∶0.5∶0.75∶0.75,其中,Pd、Cu、Fe为催化剂活性组分,Ce、La为催化助剂.用甲基橙模拟偶氮染料废水,采用催化湿式氧化法对其进行处理(甲基橙模拟废水的浓度为238 mg/L).分别测定不同反应时间水样的pH和吸光度,对其活性进行评价;分别对使用前后的催化剂进行XRD和FT-IR表征,对其稳定性进行评价.本实验制备的贵金属钯复合催化剂处理模拟废水,脱色率可达99%以上.使用前后催化剂的XRD和FT-IR谱图表征无明显变化.结果表明,贵金属钯复合催化剂活性高,稳定性好.     

Catalytic oxidation of cyclopentene to glutaraldehyde over WO3/Ti–HMS catalyst

A PdZn alloy-based catalyst was prepared by impregnation with a Pd salt of the oxides obtained by the thermal decomposition of a Zn–Al hydrotalcite. Two samples were obtained by carrying out the reduction at 373 and 673 K, that were characterized by chemical analysis, powder XRD and TEM. The catalytic activity was tested in the low pressure hydrogenation of acetophenone. The results were compared with those obtained using a conventional palladium catalyst.     

Influence of Pd Precursor and Method of Preparation on Hydrodechlorination Activity of Alumina Supported Palladium Catalysts

A series of alumina supported Pd catalysts were prepared by the novel deposition-precipitation method adopting the chloride precursor (DP-Cl) of Pd and varying the metal content from 0.25 to 1.0 wt%. The catalytic properties of prepared catalysts were studied by various characterization techniques such as N₂ adsorption, CO chemisorption, TPR, XRD, XPS, and TEM techniques. The activity and stability of the catalysts were evaluated for the gas phase hydrodechlorination (HDC) of chlorobenzene operating at atmospheric pressure. At 1 wt% of Pd the catalyst showed higher chlorobenzene conversion with good stability when tested for a period of 25 h, whereas the other catalysts exhibited a loss in activity with time. In order to elucidate the exceptional activity and stability of this catalyst, a few more catalysts with 1 wt% Pd were prepared by impregnation technique and also using a non-chloride precursor, palladium nitrate. The 1 wt% DP-Cl catalyst again was found to be the best among the others. The activity and stability of the DP-Cl catalyst was also found to be superior to two low-dispersed catalysts, each with 10 wt% Pd, prepared by conventional impregnation method using the chloride and nitrate as the precursors. The characterization results reveal that the high activity and stability of the DP-Cl catalyst is related to the formation of electron deficient Pd species and its stabilization in the octahedral vacancies of alumina.     

Highly selective Pd/KX catalysts for low-pressure one-step synthesis of 2-ethylhexanal from n-butyraldehyde and hydrogen

2-ethylhexanal (2EH) was directly synthesized from n-butyraldehyde and hydrogen at 1 atm and 150°C using the catalysts prepared by supporting tetraamine palladium(II) chloride on the potassium ion-exchanged zeolite X (Pd/KXW) and on the potassium ion-added zeolite X (Pd/KXU). The latter catalyst contains a larger amount of potassium ion and exhibits higher activity and very high selectivity of 2EH (>93%) due to its greater basicity. The main reaction path possibly starts from self-condensation of n-butyraldehyde on the catalyst basic sites to form 2-ethyl-3-hydroxyhexanal followed by dehydration to 2-ethyl-2-hexenal which was then hydrogenated on the metallic Pd sites to 2EH. This revised version was published online in July 2006 with corrections to the Cover Date.     

合成氯乙烯低汞催化剂制备

采用不同工艺条件制备氯乙烯低汞催化剂,利用固定床反应器对催化剂进行活性评价,筛选转化率和选择性较高的催化剂制备条件。结果表明,与等体积浸渍法相比,由于过饱和浸渍法制得的催化剂负载更多的Hg Cl2,在反应前期,催化剂活性较低,随着反应时间的延长,催化剂被完全激活,活性超过等体积浸渍法制备的催化剂。浸渍时间、水浴温度和溶液p H均影响活性炭对Hg Cl2的吸附量,在浸渍时间6 h、水浴温度60℃和p H=1条件下,控制Hg Cl2质量分数为5.35%,120℃干燥20 h制备的催化剂具有较理想的活性。复合助剂的加入有助于提高催化剂活性与热稳定性,当n(Hg Cl2)∶n(Ce Cl3)∶n(KCl)=1∶1∶1时拥有更高活性,添加更多助剂堵塞活性炭孔道,降低催化剂活性。     

Catalytic behaviour of Pt or Pd metal nanoparticles–zeolite bifunctional catalysts for n-pentane hydroisomerization

Bifunctional catalysts based on acidified Mordenite or ZSM-5 and platinum or palladium as metal function, were tested for n-pentane hydroisomerization. Two methods were used to introduce platinum: wetness impregnation and microemulsion; palladium was introduced via an organometallic complex. A lower catalytic activity was obtained for palladium catalyst in comparison with platinum samples which is explained by the lower activity of Pd in the dehydrogenation reaction step. Different catalytic behaviour of systems based on Mordenite and ZSM-5 was attributed to zeolite pore structure. The uncompleted removal of surfactant during calcination could explain the lower activity showed by catalysts prepared by microemulsion.     

一步吸附法纯化制取食品级氯化钾实验研究

青海盐湖生产的工业氯化钾有浮选剂残留和重金属超标,将其纯化应用于食品级氯化钾可以获得巨大的经济效益。以废弃物鱼鳞为原料通过活化制得鱼鳞活性炭,以鱼鳞活性炭为吸附剂采用一步吸附法同时去除盐湖工业氯化钾中的重金属铅离子[Pb（Ⅱ）]和有机胺可获得食品级氯化钾。研究结果表明:鱼鳞经过水煮和磷酸浸渍预处理,再经过550 ℃煅烧,可制得比表面积为496.152 m²/g的鱼鳞活性炭;鱼鳞活性炭纯化工业氯化钾的过程,离子交换吸附主导了鱼鳞活性炭对Pb（Ⅱ）的吸附,而静电相互作用和范德华力相互作用在鱼鳞活性炭对十八胺的吸附过程中发挥了重要作用;当鱼鳞活性炭投加量≥7 g/L时,纯化后的工业氯化钾中重金属Pb（Ⅱ）和有机胺的含量均符合GB 25585—2010《食品添加剂:氯化钾》的要求,实现了活性生物炭一步吸附法由盐湖工业氯化钾制备食品级氯化钾。     

Ethylenediamine-functionalized activated carbon anchored palladium complex: a recyclable catalyst for Heck reaction

Ethylenediamine-functionalized activated carbon anchored palladium catalyst was prepared via grafting ethylenediamine onto chemically modified activated carbon, followed by the reaction with palladium chloride and then the reduction with potassium borohydride. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results indicated that palladium immobilized on the carrier via coordination bond in this catalyst. Transmission electron microscopy images showed that the supported palladium is in the form of near spherical particles smaller than 10 nm diameter and evenly dispersed on the surface of the carrier. This catalyst was applied for the Heck reaction of aryl halides with olefins. The influences of solvents, bases, reaction temperatures and times on catalytic property of the catalyst were investigated by using the coupling of iodobenzene and styrene as a probe reaction. By varying the combination of aryl halides and olefins, this catalyst showed effective catalytic activities to produce corresponding coupling products with moderate to excellent yields. Moreover, it can be recovered by simple filtration and reused several times without significant loss of activity and selectivity.     

Catalyst preparation and deactivation issues for nitrobenzene hydrogenation in a microstructured falling film reactor

Hydrogenation of nitrobenzene to aniline in ethanol was performed continuously in a microstructured falling film reactor at 60 °C, 1–4 bar hydrogen pressure and residence time 9–17 s. Palladium catalyst was deposited as films or particles via sputtering, UV-decomposition of palladium acetate, incipient wetness or impregnation. Deactivation was observed and was particularly pronounced for the sputtered and UV-decomposed catalysts. Catalysts prepared through incipient wetness or impregnation were more stable and activity could be recovered by oxidation at 130 °C. The main causes of deactivation were determined to be deposition of organic compounds and palladium loss.     

Pd-Cu/γ-Al_2O_3双金属催化剂脱除水中硝酸盐

采用分步浸渍法和共浸渍法制备系列Pd负载质量分数为1%的Pd-Cu/γ-Al2O3双金属催化剂,以氢气为还原剂研究其对水中硝酸盐催化脱除的性能。结果表明,催化剂中Cu与Pd物质的量比以及Cu、Pd的浸渍顺序对催化剂性能有重要影响,硝酸根转化率随着Cu与Pd物质的量比的增大而增大;硝酸根转化活性以Cu与Pd物质的量比为5∶1、先浸渍Pd再浸渍Cu所得催化剂较优;从氨氮选择性方面看,以先浸渍Cu后浸渍Pd制备的催化剂选择性较低,在Cu与Pd物质的量比为1∶1、先浸渍Cu再浸渍Pd所得催化剂较优。