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1.
以HZSM-5与硫酸铜为原料制备催化剂Cu-ZSM-5。探讨了以Cu-ZSM-5为催化剂,二甘醇脱水制备1,4-二氧六环的工艺。催化剂的性能主要通过二甘醇的转化率和1,4-二氧六环的选择性来评价。分别研究了催化剂用量、反应温度和反应时间对二甘醇转化率及1,4-二氧六环选择性的影响。较优的反应条件为:催化剂用量为总反原料质量的4.7%,控制反应温度180℃左右,反应300min,二甘醇的转化率为95.1%,1,4-二氧六环的选择为性86.1%,且催化剂可以多次循环使用。 相似文献
2.
以乙二醇为原料,采用颗粒型SO2-4/MxOy固体超强酸催化剂,在常压、气相条件下,固定床催化合成了1,4-二氧六环;同时考察了不同反应温度、原料配比、进料速度等条件对催化反应的影响,并对上述影响因素进行了探讨.产品经气相色谱,红外光谱及质谱分析,结果表明,原料在260℃温度条件下,以进料流速为0.12 mL/min为最佳反应条件,在该实验条件下,1,4-二氧六环的生成产率达到60%~70%左右.该合成工艺应用固体超强酸催化剂具有较高的催化活性、化学稳定性好、无环境污染,是工业生产1,4-二氧六环较理想方法,具有良好的工业生产前景. 相似文献
3.
采用间苯三酚与对苯二甲醛缩聚得到的树脂为碳前驱体,分别以1,4-二氧六环与去离子水为溶剂,以溶剂热和水热法、氯磺酸为磺化试剂制备两种磺化碳基固体酸催化剂。SEM、XPS和TGA等分析表明,以1,4-二氧六环为溶剂合成的TP-A-S催化剂为形貌规整、高酸密度、良好稳定性的球形,并表现出良好的催化性能。将其用于油酸与甲醇的酯化反应,最适宜的条件为:醇油物质的量比10∶1,催化剂用量占原料总质量的2.0%,反应温度70℃,反应时间4h,油酸最高转化率达98.3%。且催化剂循环使用5次后,油酸转化率仍达84.4%。将制备的TP-A-S催化剂用于长链游离脂肪酸与甲醇的酯化反应,转化率高于90%,表现出良好的催化效果。 相似文献
4.
以对甲苯磺酸作催化剂,对乙二醇脱水制备1,4-二氧六环的反应进行研究。考察了催化剂用量、反应时间和反应温度等因素对收率的影响,得出最佳反应条件:催化剂用量为乙二醇质量的4.3%,反应时间50 min,收率可达84.82%。 相似文献
5.
以活性炭(AC)为载体,采用浸渍法制备Pd/AC催化剂,并利用XRD,BET,SEM,TEM等表征手段对AC和Pd/AC进行表征,结果表明,活性组分Pd在活性炭上分散均匀。研究了Pd/AC为催化剂,常压下对1,4-二氯苯(1,4-DCB)进行催化加氢脱氯。在以甲醇为溶剂,2 m L,12.5 g/L 1,4-二氯苯-甲醇溶液为反应原料,Pd/AC催化剂用量为100 mg,反应温度35℃,反应时间为4 h和常压氢气条件下,1,4-DCB的去除率达到100%,苯收率为100%。Pd/AC催化剂套用5次后活性下降,主要原因为有机物沉积和活性组分Pd团聚。 相似文献
6.
1,4-二氧六环是一种优良溶剂,与水和许多有机溶剂混溶,是很好的有机溶剂,它已广泛用于化学工业、药物合成、农业化学、电子工业及光敏树脂等领域。采用乙二醇生产的副产物二甘醇(一缩二乙二醇)为原料合成1,4-二氧六环是最经济工艺路线,本技术特点是使用沸石催化剂催化合成1,4-二氧六环克服了传统工艺使用硫酸催化剂或其它液体酸催化剂对设备腐蚀严重.废物处理繁杂, 相似文献
7.
研究了在对甲基苯磺酸作用下,一缩二乙二醇脱水制取1,4-二氧六环的工艺方法和操作条件。实验考察了催化剂种类,催化剂用量、反应温度、反应时间等因素对1,4-二氧六环收率的影响,用对甲基苯磺酸作催化剂,1,4-二氧六环收率达92%。采用萃取分离反应产物,确定了较理想的萃取剂,并考察了萃取剂用量对萃取率的影响。 相似文献
8.
以活性炭为载体,通过浸渍法制备了H9P2W15V3/C催化剂,对催化剂进行FT-IR表征。以催化1,4-丁二醇脱水制备四氢呋喃为探针反应,考察催化剂的酸催化性能。通过正交实验得出了最佳条件反应:w(催化剂)=3.93%(相对1,4丁二醇质量),反应温度为185~190 ℃,反应时间为40 min,四氢呋喃平均收率达93.30%,催化剂重复使用3次,产率仍可达90.94%。本工艺具有绿色、安全、操作简单、收率高等优点。 相似文献
9.
文章重点阐述了一种适合工业化大生产的高纯度1,4-二氧六环-2-酮(PDO)单体的制备方法,以乙二醇、氢氧化钠、氯乙酸钠为起始原料,一锅法合成β-羟基乙氧基乙酸钠,再在相转移催化剂作用下与氯甲酸酯反应,得到产品PDO,精制后其纯度可达99.9%以上,长期低温保存质量稳定。 相似文献
10.
本文采用浸渍法制备得到5%Pd/MIL-101(Cr)催化剂,利用XRD、扫描电子显微镜(SEM)等表征手段对催化剂进行表征,考察了溶剂、催化剂与底物丁炔二醇物质的量之比、反应温度、H_2压力及反应时间等因素对1,4-丁炔二醇加氢制备1,4-丁烯二醇的影响。结果表明,以甲醇作为反应溶剂,催化剂中心金属Pd与底物物质的量之比为1∶4000,反应温度为90℃、H_2压力为4.5MPa下反应25min的条件下,1,4-丁炔二醇转化率为97.6%,生成1,4-丁烯二醇选择性达到了96.3%。 相似文献
11.
The hydration of ethene was carried out over H 3PO 4/SiO 2 having various amounts of H 3PO 4. The rate of the ethanol formation increased markedly with the increasing H 3PO 4 loadings, in particular above 60–70 wt%. By X-ray diffraction (XRD), and and MAS NMR methods, it was revealed that various silicon phosphates were produced in the preparation of the catalysts. The structures of the phosphates depended on the H 3PO 4 loadings. It was suggested that Si(HPO 4) 2·H 2O species which formed at higher H 3PO 4 loadings were hydrolyzed to H 3PO 4 and SiO 2 during the course of the reaction, yielding the catalysts with high performance. The bulk phase of the H 3PO 4 was involved in the reaction. 相似文献
12.
合成气经草酸二甲酯加氢制乙二醇技术在工业应用过程中存在一些技术难题,其中草酸二甲酯加氢制乙二醇催化剂的稳定性是制约该技术发展的瓶颈。以Cu/SiO_2草酸二甲酯加氢催化剂A为研究对象,通过2 600 h的稳定性实验研究,考察反应温度对草酸二甲酯转化率、乙二醇选择性以及产物中乙醇酸甲酯含量的影响,为合成气经草酸二甲酯制乙二醇技术的工业应用优化提供重要的技术支持。结果表明,当反应压力2.8 MPa、空速(0.3~0.5)h-1、氢酯物质的量比120~140和反应温度216℃时,草酸二甲酯转化率近100%,乙二醇选择性大于95.0%,产物中乙醇酸甲酯质量分数小于0.5%,Cu/SiO_2催化剂A稳定性较好。 相似文献
13.
采用V_2O_5/WO_3-TiO_2作为脱硝催化剂,考察活性组分V_2O_5和助剂WO_3负载量对催化剂脱硝活性和抗硫抗水性能的影响。结果表明,3%V_2O_5/x WO_3-TiO_2催化剂(x=3%、4%、5%、6%、7%、8%、9%、10%)上NOx转化率随着WO_3负载量增加而升高,催化剂反应温度窗口不断拓宽。单独通水蒸汽及同时通SO2和水蒸汽对催化剂的毒害作用均较强,表明H2O和NH3的竞争吸附是催化剂抗硫抗水性能较差的重要原因。SO_2与H_2O和NH_3反应生成亚硫酸铵盐和硫酸铵盐,导致催化剂孔隙堵塞,催化活性降低。 相似文献
14.
The catalytic generation of H 2O 2 from H 2 and O 2 has been studied over zeolite beta-supported Pd and zeolite beta-adsorbed organic compounds such as 1,4-benzoquinone (BQ), hydroquinone (HQ), azobenzene (AB) and hydrazobenzene (HAB). According to catalytic results, zeolite beta-supported Pd catalysts display effective performance relative to those prepared from other types of zeolites reported and Pd-loaded zeolite beta-adsorbed HQ catalysts show enhanced activity compared to zeolite beta-supported Pd catalysts. In situ UV–Vis spectroscopic study indicates that HQ can readily be converted to BQ reversibly under H 2 and air inside zeolite beta only in the presence of Pd. The results suggest that HQ acts as a strong hydrogen transfer agent to promote the production of H 2O 2 from H 2 and O 2 in cooperation with a Pd catalyst. By contrast, adsorption of BQ, AB and HAB induces suppression of the catalytic properties of Pd/zeolite beta. 相似文献
15.
Conversion of NO x with reducing agents H 2, CO and CH 4, with and without O 2, H 2O, and CO 2 were studied with catalysts based on MOR zeolite loaded with palladium and cerium. The catalysts reached high NO x to N 2 conversion with H 2 and CO (>90% conversion and N 2 selectivity) range under lean conditions. The formation of N 2O is absent in the presence of both H 2 and CO together with oxygen in the feed, which will be the case in lean engine exhaust. PdMOR shows synergic co-operation between H 2 and CO at 450–500 K. The positive effect of cerium is significant in the case of H 2 and CH 4 reducing agent but is less obvious with H 2/CO mixture and under lean conditions. Cerium lowers the reducibility of Pd species in the zeolite micropores. The catalysts showed excellent stability at temperatures up to 673 K in a feed with 2500 ppm CH 4, 500 ppm NO, 5% O 2, 10% H 2O (0–1% H 2), N 2 balance but deactivation is noticed at higher temperatures. Combining results of the present study with those of previous studies it shows that the PdMOR-based catalysts are good catalysts for NO x reduction with H 2, CO, hydrocarbons, alcohols and aldehydes under lean conditions at temperatures up to 673 K. 相似文献
16.
A series of calcium-modified alumina-supported cobalt catalysts were prepared with a two-step impregnation method, and the effect of calcium on the catalytic performances of the catalysts for the partial oxidation of methane to syngas (CO and H 2) was investigated at 750 °C. Also, the catalysts were characterized by XRD, TEM, TPR and ( in situ) Raman. At 6 wt.% of cobalt loading, the unmodified alumina-supported cobalt catalyst showed a very low activity and a rapid deactivation, while the calcium-modified catalyst presented a good performance for this process with the CH 4 conversion of 88%, CO selectivity of 94% and undetectable carbon deposition during a long-time running. Characterization results showed that the calcium modification can effectively increase the dispersion and reducibility of Co 3O 4, decrease the Co metal particle size, and suppress the reoxidation of cobalt as well as the phase transformation to form CoAl 2O 4 spinel phases under the reaction conditions. These could be related to the excellent catalytic performances of Co/Ca/Al 2O 3 catalysts. 相似文献
17.
The effect of treatment with different mineral acids (H 2SO 4, H 3PO 4, HNO 3 and HCl) on the activity of monolithic CoO x/γ-Al 2O 3 catalysts in the reduction of nitric oxide with methane in the presence of oxygen (CH 4-SCR of NO x) was studied. Their behaviour in the methane oxidation reaction in both the presence and absence of NO x was determined in order to interpret the results in terms of intrinsic activity and competition between both processes. Depending on the nature of the acid used, significant differences were observed in the catalytic activities which were related to the textural states, surface acidities and the nature of the detected species. The best results were obtained after treatment with H 2SO 4, which increased the activity towards NO x elimination compared to the other catalysts. This behaviour was attributed not only to an increase in surface acidity but also to the stabilisation of the active Co 2+ species, thus avoiding the formation of Co 3O 4 spinel that is responsible for the strongly adsorbed NO x species that lead to NO 2 formation which increase the rate of the undesired methane oxidation reaction at high temperatures. 相似文献
18.
Zeolite Y supported rhodium catalysts were prepared by ion-exchange starting from an aqueous solution of [Rh[(NH 3) 5Cl]Cl 2·6H 20]. Previous work in this laboratory had shown that this procedure results in a Rh dispersion of near 100%. The catalysts were tested for their activity in the CO 2 reforming of CH 4. They were found to combine extraordinary stability with high activity and selectivity. At 923 K, 90 mol-% of the CH 4 was converted giving a H 2/CO ratio near unity. A weight loading of 0.5 to 0.93% Rh gives the highest turnover frequencies. Thermodynamic equilibrium is reached near 873 K. With a given Rh loading, the zeolite supports are superior to amorphous supports and NaY is superior to the HY. No deactivation was observed in tests of 30 h time on stream at atmospheric pressure or after repeated thermal cycles. No coke deposition was detected by temperature programmed oxidation of used catalysts. Temperature programmed reduction indicates the presence of three discernible Rh species. 相似文献
19.
以改性活性炭为载体,采用等体积浸渍法制备了La 2O 3/AC催化剂。采用XRD和BET手段对催化剂进行表征,使用微型固定床反应器考察催化剂的脱硫脱硝活性。结果表明,La 2O 3/AC催化剂对CO同时还原SO 2和NO具有良好活性,负载质量分数10%的La 2O 3/AC催化剂活性较好,SO 2和NO转化率达到90%的反应温度最低,分别为335 ℃和325 ℃;载体与活性组分之间存在协同作用,引入活性炭载体能够降低反应温度并提高催化活性。 相似文献
20.
The role of La 2O 3 loading in Pd/Al 2O 3-La 2O 3 prepared by sol–gel on the catalytic properties in the NO reduction with H 2 was studied. The catalysts were characterized by N 2 physisorption, temperature-programmed reduction, differential thermal analysis, temperature-programmed oxidation and temperature-programmed desorption of NO. The physicochemical properties of Pd catalysts as well as the catalytic activity and selectivity are modified by La2O3 inclusion. The selectivity depends on the NO/H2 molar ratio (GHSV = 72,000 h−1) and the extent of interaction between Pd and La2O3. At NO/H2 = 0.5, the catalysts show high N2 selectivity (60–75%) at temperatures lower than 250 °C. For NO/H2 = 1, the N2 selectivity is almost 100% mainly for high temperatures, and even in the presence of 10% H2O vapor. The high N2 selectivity indicates a high capability of the catalysts to dissociate NO upon adsorption. This property is attributed to the creation of new adsorption sites through the formation of a surface PdOx phase interacting with La2O3. The formation of this phase is favored by the spreading of PdO promoted by La2O3. DTA shows that the phase transformation takes place at temperatures of 280–350 °C, while TPO indicates that this phase transformation is related to the oxidation process of PdO: in the case of Pd/Al2O3 the O2 uptake is consistent with the oxidation of PdO to PdO2, and when La2O3 is present the O2 uptake exceeds that amount (1.5 times). La2O3 in Pd catalysts promotes also the oxidation of Pd and dissociative adsorption of NO mainly at low temperatures (<250 °C) favoring the formation of N2. 相似文献
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