丁腈橡胶选择性加氢新方法

发现在以往文献报道中只能催化小分子氢化反应的一类含稀土和过渡金属的金属间化合物对丁腈橡胶具有选择性催化加氢作用。该反应属于非均相常压加氢。金属间化合物的组成和不同的活化方式、溶剂等均可显著影响丁腈橡胶的加氢程度。     

丁腈橡胶的烯烃复分解及其产物的非均相加氢

采用烯烃复分解方式制备低相对分子质量的丁腈橡胶并对其进行非均相加氢,考察了烯烃复分解催化剂加入量、反应温度及反应时间对丁腈橡胶相对分子质量及其分布的影响。结果表明,在10 m L三氯甲烷中溶解1 g丁腈橡胶、催化剂用量0.001 g、反应温度30℃及反应时间3 h的条件下,所制备丁腈橡胶的数均分子量为(1.5~5.5)×104,重均分子量为(3.0~12.0)×104。采用非均相催化剂对低相对分子质量丁腈橡胶进行加氢的氢化度可达99%以上。     

丁腈橡胶非均相加氢催化剂失活原因及再生性能研究

对丁腈橡胶非均相催化加氢制备高附加值氢化丁腈橡胶过程中催化剂失活的原因进行了探究,发现造成催化剂活性下降的原因并不是贵金属纳米颗粒的流失、团聚或中毒,而是催化剂表面的活性位被聚合物覆盖而无法与反应物接触,因此将覆盖在活性位上的聚合物进行脱除才是催化剂再生和重复利用的关键。根据相似相容原理选择单溶剂或者混合溶剂对反应后催化剂进行处理,结果表明经过乙酸乙酯、丁酮、N,N-二甲基甲酰胺以及N-甲基吡咯烷酮这四种有机溶剂处理后,其催化加氢活性可以恢复至新鲜催化剂活性的90%;当用混合溶剂处理后,其催化活性可以提高至新鲜催化剂活性的95%,且循环利用4次其催化活性仍能保持不变。     

低温原位制备氢化丁腈橡胶（英文）

选用水合肼/过氧化氢/硫酸铜为催化体系,经氧化还原反应产生二酰亚胺,在5℃时对丁腈橡胶进行原位加氢,研究了催化剂体系对低温加氢反应的影响,用衰减全反射傅里叶变换红外光谱表征了低温原位制备氢化丁氢橡胶(HNBR)的加氢程度。结果表明,在低温加氢过程中,丁腈橡胶分子链中的乙烯基首先被氢化,仅有丁二烯结构单元的1,4-结构未被完全氢化;催化剂用量在加氢过程中呈S型增长趋势,HNBR产物的凝胶含量较低。     

负载型Ru/Al_2O_3催化剂催化加氢制备氢化双酚A研究

采用负载型Ru/Al_2O_3催化剂对双酚A(BPA)加氢制备氢化双酚A(HBPA)进行了研究,考察了催化剂煅烧温度、煅烧时间、还原温度、还原时间、催化剂负载量等制备条件对反应的影响,确定催化剂最佳制备条件为:煅烧温度200℃、煅烧时间5 h、还原温度100℃、还原时间1 h,Ru负载量(w)3%。同时考察了溶剂类型、催化剂用量、反应温度、反应压力等条件对催化加氢反应的影响,确定催化加氢反应的最佳工艺条件为:溶剂选用异丙醇、催化剂用量3%、反应温度160℃、反应压力4.5MPa、反应时间4 h。在上述最佳条件下,双酚A的转化率为100%,氢化双酚A的选择性为97.08%。     

氢化丁腈酯橡胶及其特性

正通过催化加氢改性不饱和聚合物是一种制备具有良好耐热、耐老化和耐臭氧氢化物的有效方法。Rempel等人以前在溶液中以RhCl(PPh3)3作为催化剂,研究了NBR加氢,结果表明在0.1MPa氢气压力和110℃下,在不同溶剂中催化活性相差很大,这是由于是在侧基上而不是在双键链上选择性加氢。例如,当使用丁酮作为溶剂时,催化反应不是在1,2和1,4-丁二烯结构上选择性     

丁腈橡胶非均相催化加氢研究进展

丁腈橡胶（NBR）选择性催化加氢是制备高附加值、高性能氢化丁腈橡胶（HNBR）的一个重要过程。将链段中C==C双键加氢饱和而保留氰基基团,不仅可保持其原有的耐油性和耐磨性,而且可极大地改善其耐侯性、耐臭氧性等。本文介绍了NBR加氢的几种工艺,着重综述了NBR非均相催化加氢的研究进展及发展方向,探讨了负载型催化剂的载体孔道结构和表面性质及活性组分组成对NBR加氢性能的影响。本文还对非均相催化加氢过程中的溶剂效应、催化剂的回收和循环再生进行了阐述,提出溶剂对催化加氢速率和加氢度都有重要影响,溶剂的受氢能力（β值）是影响加氢过程的关键参数。催化剂失活的主要原因是表面活性位点被聚合物覆盖,而利用有效的溶剂洗涤或者采用催化剂表面功能化的方式,可促使活性位再次暴露,恢复其加氢活性。最后,对非均相加氢制备高附加值HNBR体系中的催化剂设计、溶剂效应和催化剂再生等发展方向进行了展望。     

铑-钌双金属配合物催化加氢NBR胶乳

用自制的铑-钌双金属配合物催化剂对NBR乳液进行加氢反应,体系中加入适量的共溶剂以提高催化加氢效率.研究结果表明,NBR胶乳中聚合物浓度为1.81 ×10-2g/mL、催化剂用量为NBR胶乳质量的0.25%、反应温度为145℃、氢气压力为1.4MPa,以丙酮/氯苯(体积比为1/1)为共溶剂时,NBR胶乳的氢化率随加氢时间的增加而增加,12 h后氢化率达到82.1%.傅里叶红外光谱仪分析结果表明,氢化丁腈橡胶中的双键含量减少,腈基含量没有变化,因此其耐油性能未受到影响.     

国内外丁腈橡胶溶液加氢法催化剂研究进展

氢化丁腈橡胶(HNBR)具有优异的耐油性、耐热性、耐磨性、耐老化性、耐臭氧性、耐化学品性等性能,在航空航天、汽车、石油化工、纺织印染等领域应用广泛。本文总结了国内外HNBR生产供应情况,并对丁腈橡胶溶液加氢法使用的以钯(Pd)、铑(Rh)、钌(Ru)等金属为活性中心的均相和非均相配位催化剂的研究及催化剂脱除方法进行了综述分析,并对HNBR的发展趋势进行了展望。     

一种新型铑钌双金属催化剂对 NBR加氢的研究

研制了一种新型铑钌双金属加氢催化剂（BMSC）用于NBR不饱和双键的加氢，具有高活性、良好的选择性和较低的成本。通过与单金属催化剂RhCl(PPh3)3及RuCl2(PPh3)3对NBR加氢活性及加氢速率对比，表明BMSC的加氢活性与RhCl(PPh3)3的相当且无凝胶生成，其相对加氢速率从大到小为RhCl(PPh3)3，BMSC，RuCl2(PPh3)3。Raman光谱分析表明这是一种新型络合加氢催化剂，它不同于RhCl(PPh3)3和RuCl2(PPh3)3催化剂的混合物。通过红外光谱对加氢前后的NBR进行了表征，得到加氢前后—CN的特征峰(2247cm-1处)无变化,同时在3400～3500cm-1和3310～3450cm-1处未发现—NH2和仲胺的特征峰,说明—CN没有被还原。因而这是一种高活性、高选择性的NBR加氢催化剂，其加氢度可达98％以上而无凝胶生成。     

The chemical anchoring of noble metal amine precursors to silica

The effect of pretreatment on the dispersion of supported noble metal Catalyst prepared from amine precursors in basic solution have been studied. The following metal precursors were used: Pt(NH₃)₄(NO₃)₂, Pd(NH₃)₄(NO₃)₂, Ru(NH₃)₆Cl₃ and [Rh(NH₃)₅Cl]Cl₂ Pretreatment in oxygen, prior to reduction in H₂ at 400C, resulted in poor dispersions for Ru and Rh, moderate dispersions for Pd and high dispersions for Pt. Pretreatment in H₂ resulted in poor dispersions for Pd and Pt and high dispersions for Ru and Rh. Decomposition of the adsorbed Pt and Pd precursors in argon resulted in very high dispersions.     

Grafting and crosslinking reaction of carboxyl-terminated liquid rubber with silica nanoparticles and carbon black in the presence of Sc(OTf)3

The grafting of carboxyl-terminated liquid rubbers, specifically polybutadiene (BR-COOH) and nitrile rubber (NBR-COOH), was investigated in the presence of scandium trifluoromethanesulfonate (Sc(OTf)₃) as a catalyst, on silica nanoparticles and on carbon black surfaces. In the absence of the catalyst, the grafting of the liquid rubbers onto silica nanoparticles and carbon black minimally proceeded. In contrast, terminal-carboxyl groups of the liquid rubbers readily reacted with amino groups on silica and phenolic hydroxyl groups on carbon black in the presence of Sc(OTf)₃ to give BR-grafted and NBR-grafted silica and carbon black. After the grafting reaction, Sc(OTf)₃ was easily recovered and the recovered Sc(OTf)₃ could be reused in the grafting of the liquid rubbers onto silica and carbon black. In addition, when an excess of silica nanoparticle and carbon black was reacted in the absence of solvent, the crosslinking reactions of the liquid rubbers by silica nanoparticles and carbon black proceeded in the presence of Sc(OTf)₃.     

CATALYTIC HYDRODECHLORINATION OF 1,2-DICHLOROETHANE AND TRICHLOROETHYLENE OVER Rh/Si0 2 CATALYSTS

Reactions of hydrogen with 1,2-dichloroethane and trichloroethylene have been investigated over Rh/Si0 ₂ catalysts at 365-553K and 0.1 MPa. The major products of the reactions are HCl and C ₂ H ₆. The selectivity for C ₂ H ₆ increases with increasing temperature. C ₂ HC ₅ Cl is a minor product for the dichloroethane reaction; partially dechlorinated products, i.e. C ₂ H ₅ Cl, C ₂ H ₄ CI ₂, C ₂ H ₃ Cl, and C ₂ H ₂ CI ₂, constitute the minor products for the trichloroethylene reaction. The selectivity for the partially dechlorinated C ₂ hydrocarbons decreases with increasing temperature. Cl dissociated from chlorinated hydrocarbons poisons the catalyst. Regeneration of catalyst by hydrogen treatment restores the catalyst to more than 70% of the initial activity for the trichloroethylene reaction. Probing the hydrogenation activity of the used Rh/Si0 ₂ and RhCl ₃ /Si0 ₂ with ethylene hydrogenation shows that the presence of CI on Rh/Si0 ₂ decreases hydrogenation but increases ethylene hydrogenolysis activities.     

Cis–trans isomerization of olefinic alcohols promoted by Rh(I) complexes

Homogeneous hydrogenation and isomerization reaction of cis-2-butene-1,4-diol has been investigated in ethanol by using tris(triphenylphosphine)chlororhodium(I), RhCl(PPh₃)₃, and triethylamine at 303 K and 0.01–0.1 MPa partial hydrogen pressure. Under reduced H₂ pressure, the geometric isomerization reaction occurs, to a high extent, leading to trans-2-butene-1,4-diol up to 93% selectivity at 90% conversion of the cis analogous. Effects of H₂ partial pressure as well as triethylamine, added phosphine and olefin concentrations on the rate of reaction and on the products distribution were also investigated. The results obtained can be interpreted on the basis of a proposed mechanism in which RhH(PPh₃)₃ is the active species. The high selectivity towards cis-trans isomerization of cis-2-butene-1,4-diol is attributed to steric factors of the Rh(I) coordinated triphenylphosphine groups.     

Rh/SiO2催化剂上双环戊二烯氢甲酰化

采用浸渍法制备了SiO₂低负载量的铑催化剂Rh/SiO₂。研究以三苯基膦为配体的Rh/SiO₂催化剂对双环戊二烯氢甲酰化合成三环癸烷不饱和单醛的催化性能及其影响因素。结果表明,Rh/SiO₂催化剂对双环戊二烯氢甲酰化具有良好的催化作用,双环戊二烯合成三环癸烷不饱和单醛选择性超过99%。双环戊二烯氢甲酰化过程与催化剂用量、三苯基膦浓度、反应压力和反应温度有关。反应过程中存在一定诱导期,随着压力增加,诱导期逐渐缩短;增加催化剂用量和三苯基膦浓度有利于提高双环戊二烯转化率和三环癸烷不饱和单醛收率;升高温度虽然有利于双环戊二烯转化,却降低了三环癸烷不饱和单醛选择性。当催化剂与双环戊二烯质量比为1∶25、三苯基膦浓度10.0 g·L^－1、负载铑质量分数1‰、反应温度110 ℃、反应压力3.0 MPa和反应时间240 min时,双环戊二烯转化率超过99%,三环癸烷不饱和单醛选择性超过99%。     

硫化体系对氢化丁腈胶热氧老化性能的影响

系统研究了不同硫化体系对氢化丁腈胶（HNBR）力学性能和热氧老化性能的影响。结果表明：采用过氧化物/硫磺（S）体系得到的胶料其综合性能优于过氧化物体系得到的胶料,在100份HNBR中加入5份过氧化二异丙苯（DCP）和0.5份S,即DCP与S并用时,硫化胶拉伸强度可以达到23.85 MPa,在160℃×72 h热氧老化后仍可以达到20.99 MPa。热氧老化性能以DCP/S为7/0.5时最为优异。     

Reaction of 4-(naphthylmethyl)bibenzyl, thermally and in the presence of fe ( co )3 ( Pph3 )2

The reaction pathways, kinetics and mechanisms of 4-(naphthylmethyl)bibenzyl (NBBM) have been studied in order to resolve the fundamentals underlying the catalysis of coal liquefaction by Fe-based catalysts. Reactions of NBBM: ( 1 ) under nitrogen in the absence of catalyst, (2) under hydrogen in the absence of catalyst, (3) under nitrogen in the presence of the catalyst precursor Fe(CO)₃(PPh₃)₂, and (4) under hydrogen in the presence of the catalyst precursor Fe(CO)₃(PPh₃)₂ were accomplished. Thermolysis was selective for cleavage of the weak bibenzyl bond, whereas the catalyst precursor effected cleavage at the naphthyl moiety. The catalyst precursor was most effective in the presence of hydrogen, where the rate of consumption of NBBM and the selectivity of breaking the bond at the naphthalene ring both increased. Hydrogenation activity was also observed. Possible mechanisms are proposed to describe the pyrolytic and catalytic reactions of NBBM.     

Hydrogenation of Low Molecular Weight Polymers in Ionic Liquids and the Effects of Added Salt

The biphasic hydrogenations of a number of polymeric materials, polybutadiene (PBD), nitrile‐butadiene rubber (NBR) and styrene‐butadiene rubber (SBR), were investigated in a toluene/N,N′‐butylmethylimidazolium tetrafluoroborate, (BMI⁺BF₄⁻) system with a water‐soluble analogue of Wilkinson's catalyst, RhCl(TPPTS)₃ (TPPTS=triphenylphosphine, trisulfonated) at 100 °C and 3.1 MPa. The catalyst shows reasonable activity within ionic liquids with PBD although it was necessary in the case of NBR and SBR to add water as a co‐solvent to solubilize the catalyst within the ionic media. Both the extent of hydrogenation and the ratio of the internal 1,4‐olefins to vinyl 1,2‐olefins were monitored. A clear preference for the external olefins was observed even within NBR and SBR where functionalization on the polymer might enhance the degree of hydrogenation of the internal olefins. The effect of adding NaCl to the PBD system was also investigated. The addition of salt decreases the activity of the catalyst but has no effect on the preference for the hydrogenation of vinyl olefins.     

Performance of alumina-supported noble metal catalysts for the combustion of trichloroethene at dry and wet conditions

The performance of four different alumina-supported noble metal catalysts (0.5% of Pd, Pt, Rh and Ru, respectively) for the deep oxidation of trichloroethene (1000–2500 ppmV, WHSV = 55 h⁻¹) in air was studied in this work. Experiments were carried out at both dry and wet (20,000 ppm of H₂O) conditions. Catalysts were compared in terms of activity, selectivity for the different reaction products (CO₂, HCl, Cl₂, C₂Cl₄, CCl₄ and CHCl₃), and stability at reaction conditions.

As general trend, the activity of the catalysts decreases in the order Ru  Pd > Rh > Pt. Concerning to the effect of the water addition, no important effect on the catalyst activity was observed, except in the case of Pt, for which an increase of the catalytic activity was observed. Reaction mechanism (and hence product distribution) is very similar for Rh, Pd and Pt, being in these cases C₂Cl₄ the only organochlorinated by-product detected. In the case of Ru, the reaction mechanism seems to be quite different, CCl₄ and CHCl₃ being the main organic by-products.

Simple power-law kinetic expressions (first order on trichloroethene concentration for Pd, Rh and Ru, and zeroth order for Pt) provide fairly good fits for catalytic performance of the studied catalysts.

Finally, deactivation studies show that both formation of active metal chlorides (especially in the case of Rh) and fouling (especially for Pd and Pt) are the main deactivation causes.