Study of the coordinative nature of alkylaluminum modified Phillips CrOx/SiO2 catalyst by multinuclear solid-state NMR

Solid-state nuclear magnetic resonance spectroscopy was used to investigate the coordinative states of surface Al species on various alkylaluminum-modified Phillips CrOx/SiO2 catalysts.The alkylaluminum-modified Phillips CrOx/SiO2 catalysts were examined via ethylene homopolymerization.1H and 27Al magic angle spinning（MAS） nuclear magnetic resonance（NMR） spectra clearly demonstrated that the existing states of surface Al species in alkylaluminum-modified catalysts strongly depended on the type of alkylaluminum cocatalyst,concentration of alkylaluminum and the calcination temperature.1H MAS NMR spectra of alkylaluminum-modified Phillips CrOx/SiO2 catalysts,calcined at two different temperatures,exhibited similar trends in peak shift.1H spectra showed that with an increase of Al/Cr ratio and calcination temperature,the main peak shifted to high field,indicating that the dominant surface proton species changed from hydroxyl to ethoxyl and ethyl groups.27Al MAS NMR spectra showed the presence of three different coordination states（6-,5-,and 4-coordinated Al species） in the alkylaluminummodified Phillips catalysts.In comparison of different alkylaluminum cocatalysts,it was found that the reactivity of alkylaluminum modified Phillips catalyst decreased in the order of TEA〉DEAH〉DEAE.The amount of 4-coordinated Al species of Phillips catalysts modified by TEA,DEAE and DEAH also decreased in the order of TEA〉DEAH〉DEAE,indicating that the presence of 4-coordinated Al species is related to the polymerization activity.     

Synthesis of Methyl 3-Hydroxypropanoate by Hydroesterification of Ethylene Oxide over Dicobalt Octacarbonyl Catalyst

Methyl 3-hydroxypropanoate was synthesized via hydroesterification of ethylene oxide with CO in the presence of dicobalt octacarbonyl catalyst and methanol solvent. The catalyst exhibited high catalytic activity. The effect of reaction temperature, CO pressure, methanol dosage, catalyst dosage and reaction time on catalytic reaction was investigated. The test results revealed that this reaction was greatly affected by reaction temperature, but it was not significantly affected by the CO pressure, the methanol dosage, the catalyst dosage and the reaction time. Under the optimal conditions, the conversion of ethylene oxide was equal to 92.24%, while the selectivity and yield of methyl 3-hydroxypropanoate reached 88.99% and 84.35%, respectively.     

Propane Dehydrogenation on PtSnNa/AlSBA-15 Catalyst:Influence of Tin as a Promoter

PtSnNa/AlSBA-15 catalysts with different amounts of Sn were prepared for propane dehydrogenation.The catalysts were characterized by XRF,BET,H2 chemisorption,NH3-TPD,H2-TPR,and TPO techniques.Test results indicated that the presence of tin not only modified the acid function and the interfacial character between metal and support,but also reduced the coke deposition effectively.Among these catalysts investigated thereby,the PtSn(0.7%)Na/AlSBA-15 catalyst had the best catalytic performance in terms of propane conversion and stability.With the continuous addition of Sn,more amounts of Sn0 species appeared,which was unfavorable to the reaction.The PtSn(0.7%)Na/AlSBA-15 catalyst was parametrically characterized in order to obtain necessary information to integrate the process operating conditions.A weight hourly space velocity of 3 h-1,a reaction temperature of 610 ℃ and a H2/C3H8 molar ratio of 0.25 were found to be optimum conditions for achieving a higher dehydrogenation activity of the catalyst.     

二氧化硅负载Cr(acac)3/PNP催化剂的制备及其催化乙烯四聚反应性能研究

Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction pressure and Al/Cr molar ratio on ethylene tetramerization were investigated in detail. Chromium was uniformly and firmly immobilized on the support and could not be leached off by methylaluminoxane. The supported catalyst, upon being activated with methylaluminoxane, exhibited catalytic activity of 1.70×107 g/(mol Cr·h) for ethylene tetramerization to form 1-octene at a reaction temperatures of 80 ℃, a pressure of 2.0 MPa and an Al/Cr molar ratio of 300. The supported catalyst presented a good tolerance to high temperature.     

Cp*Ti(OBzOCH3)3/mMAO催化1-丁烯的聚合

Tri(4-methoxy-1-benzyloxyl)(pentamethylcyclopentadienyl)titanium(Cp*Ti(OBzOCH3)3) in conjunction with modified methylalumoxane(mMAO) was an efficient catalyst for the living polymerization of butene-1. The steric and highly electron-releasing nature of the catalyst was probably responsible for the resulting polymers with high molecular weight and narrow molecular weight distribution(Mw/Mn=1.25 to 1.36). The effects of polymerization conditions on the catalytic activity, molecular weight and stereo-regularity of the products were investigated in detail. Especially, the content of TMA in MAO used in polymerization of butene-1 had a profound influence on polymer microstructure. The structural properties of the polybutene-1 product were characterized by 13 C NMR, GPC, DSC and WAXD. The results indicated that the polybutene-1 was isotacticity-rich(at 0 ℃, [mmmm] reached up to 60.3%) and the relative content of methylene pentad sequences [mmmm] of the polymer increased with a decreasing temperature.     

ZrOCl2?8H2O: 一种低廉高效的催化剂在酯化反应中的应用

The esterification of lauric acid with methanol could be efficiently catalyzed by ZrOCl2·8H2O, and this reaction was studied to develop a green method for biodiesel production. The influencing factors, such as amount of catalyst, reaction time and molar ratio of acid to methanol, were investigated. The results indicated that the ZrOCl2·8H2O catalyst showed high catalytic activity, and gave a 97.0% methyl laurate conversion rate under the following optimized conditions, viz.: a lauric acid/methanol molar ratio of 1:10, a catalyst dosage of 4%, and a reaction duration of 2 h at methanol refluxing temperature. The catalyst could be easily recovered while its activity could be well retained after three cycles. The ZrOCl2·8H2O catalyst also exhibited excellent catalytic activity for the esterification of different free long-chain fatty acids(including nonedible oils with high acid value) with different short carbon chain alcohols. Therefore, the ZrOCl2·8H2O catalyst has good potential for the synthesis of biodiesel from low-cost feedstocks such as waste vegetable oils and non-edible oils.     

水溶性双金属催化剂催化氯代硝基苯高效选择性加氢制备氯代苯胺

Selective hydrogenation of chloronitrobenzene(CNB) to chloroaniline(CAN) catalyzed by water-soluble Ru/Pt bimetallic catalyst in an aqueous-organic biphasic system was studied. It was found that the catalytic activity increased obviously due to the addition of platinum. Ru/Pt bimetallic catalysts exhibited a strong synergistic effect when the molar ratio of Pt was in the range of 5%—80%. Under the mild conditions including a temperature of 25 ℃, a hydrogen pressure of 1.0 MPa and a Pt molar ratio of 20%, the conversion of p-chloronitrobenzene(p-CNB) reached 99.9%, with the selectivity to p-chloroaniline(p-CAN) equating to 99.4%. The Ru/Pt catalyst also showed high activity and selectivity for the hydrogenation of other chloro- and dichloro-nitrobenzenes with different substituted positions. In addition, the catalyst can be recycled five times without significant loss of activity.     

Pd nanoparticles immobilized on MIL-53(Al) as highly e ective bifunctional catalysts for oxidation of liquid methanol to methyl formate

A series of Pd/MIL-53(Al) heterogeneous bifunctional catalysts with di erent Pd contents were prepared by an impregnation method. The prepared metal–organic frameworks MIL-53(Al) and catalysts were characterized by XRD, SEM, HRTEM,FT-IR and N2 adsorption/desorption techniques. The results showed that MIL-53(Al) was synthesized successfully, and the structure was unchanged during and after the preparation of the catalysts. The Pd nanoparticles(NPs) with an average particle size of 4.6 nm were uniformly dispersed on the MIL-53(Al). The catalyst exhibited good catalytic activity in the selective oxidation of liquid methanol to methyl formate. Under the conditions of 150 °C, 2 MPa O_2 and solvent-free for5 h, the conversion of methanol could reach 60.3%, and the selectivity of methyl formate was up to 62.2%. In addition, the Pd/MIL-53(Al) bifunctional catalyst exhibited excellent stability and maintained high catalytic activity after five cycles.     

ELUCIDATION OF HYDRODESULFURIZATION AND HYDROGENATION MECHANISMS USING RADIOISOTOPE TRACER METHODS

To meet the specification of sulfur and aromatic contents in diesel fuel, it is necessary for refiners to develop a new catalyst with high activity of hydrodesulfurization and hydrogenation. In the present study, the properties of noble metal catalysts for hydrodesulfurization and hydrogenation in the presence of sulfur compounds have been investigated. The hydrogenation activity of phenanthrene (PHE) on single noble metal and double noble metal catalysts-Pt/Al2O3, Pd/Al2O3 and Pd-Pt/Al2O3 in the presence of dibenzothiophene (DBT) was performed in a fixed bed flow reactor. The Pt based catalysts revealed the similar HDS activities and higher HYD activity compared with convertional Mo based catalysts. The maximum activity was obtained around 320℃ for both catalyst types. The Pt based catalysts produced perhydrophenanthrene as a major product at the maximum activity in the hydrogenation of PHE while the Mo based catalysts produced octahydrophenanthrene. A ^35S radioisotope pulse tracer method (^35S RPTM) was used to estimate the behavior of sulfur on the working catalysts and to clarity the differences between Pt and Mo based catalysts. Very little amount of labile sulfur was accumulated on the Pt and Pd catalysts in the HDS of [^35S]DBT (PtS0.25 or PdS0.25). This indicates that the mechanism of DBT HDS on noble metal catalysts is significantly different from that on conventional Mo based catalysts where Mo is present as MoS2 less than 60% of which can be labile in the case of Co-Mo/Al2O3. Another Ru-Cs/Al2O3 catalysts were also prepared and the behavior of sulfur on the working catalyst was compared with those of Mo based catalysts and Pt and Pd catalysts. The values of labile sulfur in the kIDS reaction for Ru-Cs catalysts approximately correspond to RS0.5-0.74. These amounts of labile sulfur are much higher than those for Pt and Pd catalysts. The result suggests that the oxidation state of Ru species is present between the oxidation states of Pt or Pd and Mo, and can change in the wide range during the HDS reaction, different from PtS0.25 (PdS0.25) and MoS2 which is unchangeable under the usual HDS conditions. From the approach of using [^35S]H2S it was found that the labile sulfur was hardly formed during the presulfiding procedure but was formed only during the actual HDS. This is also a unique character of Ru catalysts.     

NEW REFORMING CATALYST DEVELOPED BY RIPP

To meet the demands for high-octane gasoline and aromatics,catalytic reforming process has been advancing quickly in China.The reforming catalysts developed by RIPP have been used in more than 80% capacity of domestic CCR and SR units.This paper introduces the properties of PSVI CCR catalyst developed by RIPP in recent years and also the result from commercial units.The PS-VI catalyst has high activity and good selectivity,under the same reaction conditions,the carbon on catalyst was lowered by 26% in mass as compared with that of the reference catalyst.Among the SR reforming catalysts,the new type of PRT series catalysts have excellent performance at low reaction pressure compared with the ref.Cat A.The aromatics and reformate mass yields of PRT catalyst were 2%-3% and 3%,respectively ,higher than those of Cat A,and the run length was 30%-40% longer as well,which exhibits good prospect of application.     

以磺酰胺类为内给电子体的丙烯聚合催化剂

Three sulfonyl aliphatic amines [(R2SO2)2NR1, viz.: compound 1, in which R1=Me, and R2=Ph; compound 2, in which R1=n-Bu, and R2=CF3; and compound 3, in which R1=C8H17, and R2=CF3] have been synthesized and employed as internal electron donors (IED) for the preparation of Ziegler-Natta catalysts for the polymerization of propylene. The contents of Ti, H and C in these catalysts have been determined by elemental analysis and UV-vis spectrophotometry. The effect of the structure and dosage of the electron donor, the Al/Ti ratio and the polymerization temperature on the catalyst performance has been studied. Under optimized conditions, the catalyst with a highest activity yielded polypropylene with high isotacticity in the absence of external electron donors.     

TiCl_4/SiO_2-MgCl_2复合载体催化剂用于丙烯本体聚合的研究

以S iO2和M gC l2为复合载体,制备了T iC l4/S iO2-M gC l2复合载体催化剂,并将该催化体系用于丙烯聚合,研究了催化剂及聚合物的形态及孔特征,考察了助催化剂浓度、外给电子体浓度、氢气加入量及聚合温度等对催化剂性能的影响。实验结果表明,该催化剂的粒径分布窄,具有较大的孔体积和孔径,制得的聚丙烯也具有孔隙率高、孔径大等特点;铝钛摩尔比为600、铝硅摩尔比为20时,该催化剂具有获得较高的催化活性,同时聚丙烯具有较高的等规度;该催化剂具有较好的氢调敏感性,在较高的熔体流动指数下聚丙烯仍具有较高的等规度;随聚合温度的升高,该催化剂的催化活性以及聚丙烯的等规度均增加,聚丙烯的熔体流动指数则先减小后增加。     

ClMg(OR)·ROH负载的高效丙烯聚合催化剂及其聚合行为

以含镁配合物ClMg(OR).ROH为载体制备了高效丙烯聚合催化剂,对催化剂进行了聚合反应动力学研究,考察了聚合温度、铝钛比、铝硅比和氢气加入量对催化剂聚合反应性能的影响。实验结果表明,该催化剂具有良好的氢调敏感性和立体定向性,动力学行为呈现典型的上升-衰减型,聚合过程中聚丙烯形态复现了催化剂的形态。在三乙基铝为助催化剂、甲基环己基二甲氧基硅烷为外给电子体、n(Al):n(Ti)=300、n(Al):n(Si)=15、氢气加入量(质量分数)为0.0200%、温度为70℃的条件下,该催化剂具有较高的活性(12.0kg/g),聚丙烯等规度可达97%以上。     

MgBu_2/AlEt_2Cl为助催化剂丙烯聚合动力学

使用催化剂MgCl_2/C_4H_4(COOC_4H_9)_2/TiCl_4和混合烷基金属助催化剂MgBu_2/AlEt_2Cl在30—80℃,系统压力为1.04×10~5Pa(绝对)的条件下进行了丙烯聚合动力学研究。讨论了[Al]/[Ti]和[Mg]/[Al]对催化活性、聚合物的等规度以及分子量分布的影响。结果表明混合烷基金属助催化剂的浓度对聚合速度的影响仍可用Langmuir-Hinsbelwood机制来描绘。研究了温度与隹化活性和等规度的关系,表明超过50℃活性降低,接近50℃时等规度出现最大值。随着聚合温度的增加聚丙烯的分子量变小,尤其当温度高于60℃时这种变化更为明显。     

球形TiCl_4/MgCl_2催化剂催化丙烯聚合

以乳化急冷法制备的球形M gC l2为载体,制备了球形T iC l4/M gC l2催化剂(简称催化剂),并将该催化剂用于丙烯聚合。采用扫描电子显微镜、N2吸附法对催化剂及聚合物的形态进行了表征,考察了聚合时间、聚合温度、铝钛比、铝硅比、氢气加入量对催化剂性能的影响。实验结果表明,催化剂与聚合物均为球形,且催化剂粒径分布窄,具有较大的孔体积和孔径,所制得的聚丙烯也具有孔隙率大、孔径大等特点。较佳的聚合条件为:聚合温度70~75℃、聚合时间3h、铝与钛摩尔比为300、铝与硅摩尔比为15、氢气加入量(质量分数)2.00×10-4;在此条件下,催化剂具有较高的催化活性,同时聚丙烯具有较高的等规度;催化剂具有良好的氢调敏感性。     

剥离型聚丙烯-蒙脱土纳米复合材料Ⅰ.Ziegler-Natta/有机改性蒙脱土复合催化剂催化丙烯聚合

采用化学反应法制备了Z ieg ler-Natta/有机咪唑盐改性蒙脱土复合催化剂(简称复合催化剂),并通过丙烯单体原位插层聚合制备了聚丙烯-蒙脱土纳米复合材料。考察了n(A l)∶n(T i)、聚合温度、聚合时间及溶剂种类对复合催化剂的活性及定向催化能力的影响。研究结果表明,与商品化CS-2型Zieg ler-Natta催化剂相比,复合催化剂的活性明显降低,在n(A l)∶n(T i)=100、聚合温度60℃、聚合时间1h、正庚烷为溶剂时,复合催化剂的活性较高,可达78.4kg/(m ol.h)。合成聚丙烯的等规度在85%~97%之间,熔融温度在160℃左右,重均相对分子质量达到(3.6~4.6)×105,相对分子质量分布在6.1~6.6之间。溶剂种类对合成聚丙烯的等规度影响较大。     

丙烯聚合高效负载型Ziegler-Natte催化剂 Ⅱ.Al/Ti比和聚合温度的影响

考察助催化剂浓度（Ａｌ／Ｔｉ摩尔比）和聚合温度对ＭｇＣｌ２／ＴｉＣｌ４／ＤＮＢＰ－ＡｌＥｔ３／ＤＰＤＭＳ催化体系聚合行为的影响。发现Ａｌ／Ｔｉ摩尔比对含给电子化合物和不含给电子化合物的催化体系有不同的影响。Ａｌ／Ｔｉ摩尔比增大使含给电子化合物的催化剂活性升高，但产物的全同指数下降；使不含给电子化合物的催化剂活性降低，但全同指数提高。Ａｌ／Ｔｉ摩尔比对聚合活性的影响符合Ｌａｎｇ－ｍｕｉｒ－Ｈｉｎｓｈｅｌｗｏｏｄ竞争吸附模型。当聚合温度为５０℃时，催化剂活性最高，但聚合温度对聚合物全同指数的影响较小；在３０～５０℃之间，聚合符合Ａｒｈｅｎｉｕｓ方程；当聚合温度超过５０℃时，由于聚合物粒子形态发生变化，结果偏离Ａｒｈｅｎｉｕｓ方程。     

新型聚丙烯催化剂的性能研究

根据气相法生产均聚双向拉伸聚丙烯的特点,制备了定向能力易于随助催化剂与外给电子体的摩尔比(铝硅比)变化而调节的NA-Ⅱ型Ziegler-Natta聚丙烯催化剂。对比了NA-Ⅱ型催化剂与其他两种参比催化剂的组成、形态和粒径,并研究了铝硅比对催化剂定向能力的影响。分别以二异丁基二甲氧基硅烷和二异丙基二甲氧基硅烷为外给电子体对NA-Ⅱ型催化剂及两种参比催化剂的均聚和共聚性能进行了研究。实验结果表明,NA-Ⅱ型催化剂具有较好的颗粒形态,氢调敏感性较好,聚丙烯的等规度易于调控。     

AlCl3/TiCl4催化癸烯聚合制润滑油基础油的研究

以AlCl3/TiCl4为催化剂对癸烯聚合制润滑油基础油进行了研究。考察了催化剂用量、Al与Ti摩尔比、反应时间和反应温度等工艺条件对合成油性质的影响，并比较了不同催化剂、不同烯烃原料对聚α-烯烃(PAO)性质的影响。结果表明，癸烯聚合制备PAO，AlCl3/TiCl4是较适宜的催化剂。PAO收率随着AlCl3/TiCl4催化剂用量的增大、反应温度的升高以及反应时间的延长而提高，但随着Al与Ti摩尔比的增加而迅速下降；粘度指数在所考察的条件范围内均较高；100 ℃下的运动粘度随着Al与Ti摩尔比的变化而急剧变化，因此可以根据需求，通过调节Al与Ti摩尔比，可制备各种粘度等级的PAO产品。     

从烷基镁制备烯烃聚合催化剂

由烷基镁、氯化试剂及电子给予体制备了烯烃聚合载体催化剂。研究了Ｍｇ／酯摩尔比、氯化试剂、Ｌｅｗｉｓ碱及载钛溶剂等因素对催化剂性能的影响。由ＳｉＣｌ＿４作氯化试剂制备的载体催化剂的活性及聚丙烯等规度均高，且随Ｌｅｗｉｓ碱的烷基中碳原子数目增多，催化剂活性与聚丙烯的等规度有规律地增加。在载钛过程中，以氯苯为溶剂制备的催化剂性能最好。此外还研究了Ｍｇ／Ａｌ摩尔比、氯化试剂的种类、反应温进与搅拌速度等对载体、催化剂及聚丙烯形态的影响。在适当的条件下能得到球型载体、球型催化剂和球型聚丙烯。