磷钨酸盐催化选择性氧化苯甲醇合成苯甲醛的研究

通过两步法合成了两种磷钨酸盐催化剂,并利用13CNMR、1HNMR、IR、XRD等技术对催化剂进行了表征.表征结果显示,磷钨酸盐均具有磷钨酸的Keggin型结构.将该催化剂用于催化氧化苯甲醇的反应,以30%H2O2为氧化剂,分别考察了含不同阳离子的磷钨酸盐、反应时间、反应温度、催化剂用量和H2O2用量对反应的影响.结果...     

功能化离子液体催化合成甘油单月桂酸酯

合成了由吡啶、N-甲基咪唑、N-甲基-2-吡咯烷酮提供有机阳离子, 磷钨酸、对甲苯磺酸提供阴离子的6种离子液体。使用NMR、FT-IR和TG对离子液体表征, 并考察它们催化甘油与月桂酸酯化的催化效果。结果表明, 这些离子液体都具有较好的热稳定性, 以1-(丁基-4-磺酸基)-3-甲基咪唑磷钨酸盐离子液体的热稳定性最好。在最佳条件使用离子液体催化甘油与月桂酸反应时, 阴离子的种类对月桂酸的转化率影响较大, 以对甲苯磺酸为阴离子的离子液体催化反应时, 月桂酸转化率较以磷钨酸为阴离子的离子液体的高;1-(丁基-4-磺酸基)-3-甲基咪唑对甲苯磺酸盐离子液体做催化剂时甘油单月桂酸酯的产率最高。催化剂重复使用性方面, 离子液体重复使用5次催化活性没有明显变化。     

磷钨酸盐催化转化葡萄糖合成乙酰丙酸

制备了一系列金属离子修饰的磷钨酸盐(M_XH_3-2XPW₁₂O₄₀,M=Zn,Cu,Cs,Ag)催化剂,并将磷钨酸银盐(Ag₃PW₁₂O₄₀)用于水解葡萄糖制备乙酰丙酸的实验中。采用FTIR、XRD、SEM和EPMA等技术对磷钨酸盐性能进行了表征,并分析了磷钨酸银盐催化剂在反应前后结构和表面元素相对含量的变化。考察了反应温度、反应时间、催化剂用量和葡萄糖浓度等对乙酰丙酸得率的影响。结果表明:合成的磷钨酸盐具有磷钨酸的Keggin结构,并且Ag₃PW₁₂O₄₀催化剂在多次使用后Keggin结构没有被破坏。在催化合成反应中,在反应温度200℃、反应时间2 h、Ag₃PW₁₂O₄₀催化剂用量0.7 g和葡萄糖浓度40 g·L^-1的条件下,乙酰丙酸的最大得率可达到81.61%,催化剂可重复利用。     

壳聚糖磷钨酸盐催化合成尼泊金乙酯

以对羟基苯甲酸和乙醇为原料,用壳聚糖磷钨酸盐作为催化剂合成了尼泊金乙酯,确定了反应的最佳条件：醇酸物质的量比为5：1,催化剂用量为0．9g,反应时间3h,产品收率达87．1％。实验表明,用壳聚糖磷钨酸盐作为催化剂不仅反应时间短、活性高、酯化率高,而且催化剂又可以重复使用,从而开拓了尼泊金乙酯酯化催化剂的新领域。     

杂多酸盐催化合成柠檬酸三丁酯研究

制备了1-（3-磺酸基）丙基-3-甲基咪唑磷钼酸盐（[MIMPS]₃PMo₁₂O₄₀）、1-（3-磺酸基）丙基-3-甲基咪唑磷钨酸盐（[MIMPS]₃PW₁₂O₄₀）和1-（3-磺酸基）丙基-3-甲基吡啶磷钨酸盐（[PyPS]₃PW₁₂O₄₀）3种杂多酸盐,用于催化柠檬酸和正丁醇合成柠檬酸三丁酯（TBC）,考察了各催化剂的催化效果。其中,[MIMPS]₃PMo₁₂O₄₀具有最好的催化效果,在其催化下,考察了反应条件对酯化率的影响。结果表明：当醇酸物质的量比为4.5:1.0、反应温度为130℃、反应时间为3.5h、催化剂用量为柠檬酸质量的5%时,酯化率可达98.3%,且催化剂具有较好的重复使用性能,重复使用5次后,酯化率依然保持在94%以上。     

1-己基-3-甲基咪唑磷钨酸的制备及催化氧化环己烯制备己二酸的研究

以溴化1-己基-3-甲基咪唑离子液体和磷钨酸为原料,采用一步法合成了1-己基-3-甲基咪唑磷钨酸盐[HMIM]PW12O_40催化剂。使用红外光谱、热重分析对催化剂进行了表征。以催化氧化环己烯制备己二酸为模板反应,探讨了催化剂的催化活性。结果表明,当催化剂添加量为0.75 mmol,n(离子液体)∶n(磷钨酸)=1.5∶1,反应温度为80℃,反应时间为10 h时,己二酸产率为98.2%。催化剂在重复使用5次时,己二酸的产率为89.8%。采用design-expert对催化氧化环己烯制备己二酸进行了响应曲面建模,模型预测制备己二酸工艺参数的交互影响顺序为:(反应温度×反应时间)(反应温度×催化剂配比)(催化剂配比×反应时间)。     

1-己基-3-甲基咪唑磷钨酸的制备及催化氧化环己烯制备己二酸的研究

以溴化1-己基-3-甲基咪唑离子液体和磷钨酸为原料,采用一步法合成了1-己基-3-甲基咪唑磷钨酸盐[HMIM]PW12O_40催化剂。使用红外光谱、热重分析对催化剂进行了表征。以催化氧化环己烯制备己二酸为模板反应,探讨了催化剂的催化活性。结果表明,当催化剂添加量为0.75 mmol,n(离子液体)∶n(磷钨酸)=1.5∶1,反应温度为80℃,反应时间为10 h时,己二酸产率为98.2%。催化剂在重复使用5次时,己二酸的产率为89.8%。采用design-expert对催化氧化环己烯制备己二酸进行了响应曲面建模,模型预测制备己二酸工艺参数的交互影响顺序为:(反应温度×反应时间)>(反应温度×催化剂配比)>(催化剂配比×反应时间)。     

杂多酸及其季铵盐催化剂催化H_2O_2环氧化1-辛烯

用杂多酸与季铵盐反应制备了杂多酸季铵盐型催化剂(HQWP和Q3PW4O16),并对其进行了红外FT IR及元素分析。分别以磷钼酸,HQWP,3-氨丙基三甲氧基硅烷改性硅胶负载磷钨酸,Q3PW4O16,磷钨酸,磷钨酸钠为催化剂,H2O2为氧化剂,对1-辛烯进行环氧化反应,产率分别为3.31%、31.20%、81.42%、80.02%、94.80%、84.61%。还做了催化剂重复使用实验,其结果表明:Q3PW4O16和HQWP两种催化剂可以重复使用3次,平均产率分别为76.63%和24.54%,其他的反应产率下降明显。另外对用Q3PW4O16和HQWP为催化剂的1-辛烯环氧化反应进行了条件优化。     

磷钨酸铵铝复合盐催化合成柠檬酸三丁酯

以磷钨酸、碳酸铵和金属盐溶液为原料,制备了系列金属离子与NH_4~+复合掺杂磷钨酸盐的催化剂,并将其应用于酯化合成柠檬酸三丁酯的反应。其中,(NH_4)_(1/2)Al_(2/3)H_(1/2)PW_(12)O_(40)(Ⅰ)的催化活性较高,且成本相对较低。在正丁醇与柠檬酸的物质的量比为4∶1、催化剂Ⅰ用量为1.5%(以柠檬酸的质量为基准,下同)、温度150℃、时间3 h的条件下,柠檬酸三丁酯的收率达到97.1%。采用红外光谱、元素分析仪和Hammett指示剂法对催化剂Ⅰ的元素组成、结构、表面酸强度与酸密度进行了表征。结果表明,Ⅰ的表面酸强度(H_0)为-14.52～-13.75,表面酸密度为2.57 mmol/g,高于传统的单一掺杂磷钨酸盐。催化剂Ⅰ重复使用2次,催化活性没有明显下降。     

清洁氧化2-辛烯制备己酸

以过氧化氢为氧化剂,磷钨酸为催化剂,十六烷基吡啶为相转移催化剂催化氧化2-辛烯制备己酸;分别考察了反应温度、反应时间和催化剂物质的量对己酸收率的影响。在85 ℃和n(H₂O₂)∶n(2-辛烯)∶n(磷钨酸)∶n(十六烷基吡啶)=4.5∶1∶0.02∶0.01最佳实验条件下,己酸的收率达81.5％。     

Selective ammoximation of ketones and aldehydes catalyzed by a trivanadium-substituted polyoxometalate with H2O2 and ammonia

The ammoximation of different ketones and aldehydes to their corresponding oximes catalyzed by K₆[PW₉V₃O₄₀]·4H₂O was carried out with hydrogen peroxide and ammonia in isopropanol at room temperature. High yields of oximes were obtained in this catalytic system. This catalytic system was proved to be heterogeneous by the ammoximation activity of removal of catalyst and the elemental analysis of the filtrate after reaction. A possible procedure for the ammoximation catalyzed by K₆[PW₉V₃O₄₀]·4H₂O with H₂O₂ and NH₃·H₂O was proposed. The fresh and used catalysts were characterized by IR and ³¹P MAS NMR, which revealed the good stability of the catalyst.     

超稳Y沸石封装磷钨酸的制备、表征及其催化性能

采用“瓶中造船”方法制备了超稳Y沸石封装的磷钨酸催化剂PW-USY,并用FT-IR、UV-vis,N2吸附,NH3-TPD等手段对其进行了表征,并与浸渍法制备的负载催化剂PW/USY进行了比较,结果表明在超稳Y沸石超笼中成功合成了具有Keggin结构的12-磷钨酸。在以H2O2为氧源的环己酮氨肟化反应中,封装型磷钨酸催化剂表现出较好的催化活性,选择性较纯磷钨酸有所降低。封装型磷钨酸催化剂重复使用5次后,催化性能没有明显的下降,较负载型磷钨酸而言能较好地解决活性组分流失的问题,显示出潜在的应用前景。     

基于催化氨化反应由生物质基小分子合成腈类和吡啶碱

基于催化氨化反应以生物质基小分子合成腈类、吡啶碱等含氮化学品,不但可减少生产此类产品对化石资源的依赖,还可促进生物质基小分子产业的可持续发展。本文结合本文作者课题组的研究成果总结了近年来在乙醇、甘油催化氨化合成腈类、吡啶碱的最新研究进展。其中,乙醇可高收率地生产乙腈,也可在脱氢、适宜酸性催化剂催化下生成吡啶碱。甘油在适宜催化剂上既可以通过一步法也可以通过两步法转化为腈类和吡啶碱,其中催化剂适宜的酸性、较强的加氢-脱氢性能以及较大的比表面是决定生成何种目标产物的关键。采用两步法比一步法由甘油合成腈类和吡啶碱的收率明显提高。发现催化剂在使用中逐渐失活,而催化剂失活主要是由于亚胺中间体在催化剂酸中心的不可逆吸附,从而生成积炭所致。失活催化剂经高温有氧煅烧去除积炭可恢复其大部分活性。     

TS-1分子筛催化环己酮氨肟化反应的失活动力学

采用间歇反应器,对液相环己酮氨肟化过程中TS-1分子筛的催化活性变化规律进行了考察,在失活原因分析的基础上建立失活动力学模型:rde=1.01×1014exp(-1.17R×T105)C0A.76C0B.82C0C.38a1.64,并对模型参数进行估值。     

ZSM-5分子筛酸性和晶体大小对醛氨缩合合成吡啶碱的影响

针对Chichibabin醛氨缩合合成吡啶碱,用离子交换法制备具有相同酸性位类型,但Br?nsted(B)酸量不同的ZSM-5催化剂,并选择硅铝比接近但晶粒大小不同的H-ZSM-5分子筛,以及与ZSM-5具有相同MFI晶体结构的TS-1分子筛进行催化性能的比较。探讨了ZSM-5分子筛催化剂酸性、酸量和晶粒大小对反应活性、吡啶碱选择性和收率以及催化剂稳定性的影响。结果表明B酸位是进行醛氨缩合反应合成吡啶碱不可缺少的活性位,但酸强度较弱的末端硅羟基B酸位合成吡啶碱的活性较低;催化剂B酸含量越大,其进行醛氨缩合反应的初始活性和吡啶碱收率越高,催化剂失活越慢;小晶粒分子筛的初始活性、稳定性优于大晶粒分子筛,但合成吡啶碱的选择性和初始收率较低,这主要是因为与大晶粒分子筛相比,小晶粒分子筛具有更多的活性中心,特别是外表面活性中心,和相对较短的分子筛孔道。     

用于TS-1催化剂回收的陶瓷膜污染机理

Ceramic ultrafiltration membranes were used to separate titanium silicalite-1(TS-1) catalysts from the slurry of catalytic ammoximation of cyclohexanone to oxime.Silica was shown to have a great effect on membrane fouling in the alkaline environment of this system.In the ammoximation system,there are three main silica sources,which are residual silica on the catalyst particles surface during preparation,silica dissolved from TS-1 catalyst particles by ammonia solvent,and silica sol added into the reaction slurry to inhibit the dissolution erosion of the TS-1 catalyst.The silica dissolved by ammonia has been proved to influence membrane fouling most among the three silica sources.This was because the amount of silica dissolved by ammonia was the largest,and the polymerization of silica monomers at high concentration caused colloid particles formation,which led to a dense cake layer depositing on the membrane surface.Meanwhile,the size reduction of catalyst particles caused by alkaline dissolution also increased specific resistances of cake layers.     

Catalytic mechanism and reaction pathway of acetone ammoximation to acetone oxime over TS-1

A series of two-step reactions and several special experiments were designed and carried out to discover the reaction pathway of acetone ammoximation to acetone oxime over titanium silicalites-1 (TS-1) employing 25 wt% ammonia and 30 wt% hydrogen peroxide as the ammoximation agents. The experimental results show that the acetone oxime can form even if there is no direct contact between acetone and TS-1 catalysts, indicating the hydroxylamine route may be the most important catalytic mechanism for the reaction. HPLC, GC/MS and ion chromatography characterization results show that hydrogen peroxide can oxidize acetone oxime to acetone, nitrite and nitrate in the presence of TS-1. In addition, nitrite and nitrate can form in the reaction of H₂O₂ and NH₃ over TS-1. Based on these results, a possible overall reaction pathway of acetone ammoximation over TS-1 has been proposed.     

Ammoximation reaction in the gas and liquid phases with silica based catalysts: role of titanium

The catalytic behaviour in the liquid phase and in the gas phase ammoximation of cyclohexanone on amorphous silicas containing different amounts of titanium has been investigated. The silicas were prepared by impregnation and the sol-gel method. The behaviour of the silicas with and without titanium was different in the liquid and gas phases. The presence of titanium sites was found to be essential for the development of selectivity to oxime in the liquid phase. In the gas phase the paramount parameters are the textural and structural features of the silica and the introduction of titanium can only enhance the activity in both impregnated and sol-gel catalysts. It is proposed that the role of titanium in the gas phase is to favour the oxidation of imine, an intermediate in the vapour phase reaction, due to its ability to activate molecular oxygen.     

合成维生素E工业过程中炔醇选择性加氢催化剂的研究进展

综述了用于合成维生素E工业过程中重要炔醇,包括去氢芳樟醇、去氢橙花叔醇和去氢异植物醇,选择性加氢催化剂的研究进展。此外,毒化剂,例醋酸铅、喹啉、吡啶等,对选择性加氢催化剂的活性和选择性的影响进行了概述。最后,对这类选择性加氢催化剂的改进提出了展望。     

Catalytic activities of Co(Ni)Mo/TiO2–Al2O3 catalysts in gasoil and thiophene HDS and pyridine HDN: effect of the TiO2–Al2O3 composition

The effect of the TiO₂–Al₂O₃ mixed oxide support composition on the hydrodesulfurization (HDS) of gasoil and the simultaneous HDS and hydrodenitrogenation (HDN) of gasoil+pyridine was studied over two series of CoMo and NiMo catalysts. The intrinsic activities for gasoil HDS and pyridine HDN were significantly increased by increasing the amount of TiO₂ into the support, and particularly over rich- and pure-TiO₂-based catalysts. It is suggested that the increase in activity be due to an improvement in reducing and sulfiding of molybdena over TiO₂. The inhibiting effect of pyridine on gasoil HDS was found to be similar for all the catalysts, i.e., was independent of the support composition. The ranking of the catalysts for the gasoil HDS test differed from that obtained for the thiophene test at different hydrogen pressures. In the case of gasoil HDS, the activity increases with TiO₂ content and large differences are observed between the catalysts supported on pure Al₂O₃ and pure TiO₂. In contrast, in the case of the thiophene test, the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also, in the thiophene test the difference in intrinsic activity between the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also in the thiophene test, the difference in intrinsic activity between the pure Al₂O₃- and pure TiO₂-based catalysts is relatively small and dependent on the H₂ pressure used. Such differences in activity trend among the gasoil and the thiophene tests are due to a different sensitivity of the catalysts (by different support or promoter) to the experimental conditions used. The results of the effect of the H₂ partial pressure on the thiophene HDS, and on the effect of H₂S concentration on gasoil HDS demonstrate the importance of these parameters, in addition to the nature of the reactant, to perform an adequate catalyst ranking.