A Bifunctional Brønsted Acidic Deep Eutectic Solvent to Dissolve and Catalyze the Depolymerization of Alkali Lignin

Lignin is an abundant renewable macromolecular material in nature,and degradation of lignin to improve its hydroxyl content is the key to its efficient use.Alkali lignin(AL)was treated with Brønsted acidic deep eutectic solvent(DES)based on choline chloride and p-toluenesulfonic acid at mild reaction temperature,the structure of the lignin before and after degradation,as well as the composition of small molecules of lignin were analyzed in order to investigate the chemical structure changes of lignin with DES treatment,and the degradation mechanism of lignin in this acidic DES was elucidated in this work.FTIR and NMR analyses demonstrated the selective cleavage of the lignin ether linkages in the degradation process,which was in line with the increased content of phenolic hydroxyl species.XPS revealed that the O/C atomic ratio of the regenerated lignin was lower than that of the AL sample,revealing that the lignin underwent decarbonylation during the DES treatment.Regenerated lignin with low molecular weight and narrow polydispersity index was obtained,and the average molecular weight(Mw)decreased from 17680 g/mol to 2792 g/mol(130°C,3 h)according to GPC analysis.The lignin-degraded products were mainly G-type phenolics and ketones,and small number of aldehydes were also generated,the possible degradation pathway of lignin in this acidic DES was proposed.

Benzenesulfonic acid-grafted UIO-66 with improved hydrophobicity as a stable Brønsted acid catalyst

Hydrothermal and catalytic stability of UIO-66 MOFs with defective structures are critical aspects to be considered in their catalytic applications,especially under the conditions involving water,moisture and/or heat.Here,we report a facile strategy to introduce the macromolecular acid group to UIO-66 to improve the stability of the resulting UIO-66−PhSO3H MOF in aqueous phase catalysis.In detail,UIO-66−PhSO3H was obtained by grafting benzenesulfonic acid on the surface of the pristine UIO-66 to introduce the hydrophobicity,as well as the Brønsted acidity,then assessed using catalytic hydrolysis of cyclohexyl acetate(to cyclohexanol)in water.The introduction of hydrophobic molecules to UIO-66 could prevent the material from being attacked by hydroxyl polar molecules effectively,explaining its good structural stability during catalysis.UIO-66−PhSO3H promoted the conversion of cyclohexyl acetate at ca.87%,and its activity and textural properties were basically intact after the cyclic stability tests.The facile modification strategy can improve the hydrothermal stability of UIO-66 significantly,which can expand its catalytic applications in aqueous systems.

Brønsted-Lewis双酸性低共熔溶剂催化松香聚合反应

合成了一系列Brønsted-Lewis双酸性低共熔溶剂(DESs),并将其用于催化松香聚合反应。筛选出催化活性最高的催化剂ZnCl_(2)/2CH_(3)COOH,同时考察了不同DES物质的量比的组成,DES催化剂的用量、反应温度和反应时间对松香聚合反应的影响。最佳反应条件:松香15 g,甲苯5.6 mL,正辛烷12.4 mL,低共熔溶剂5 g,反应温度110℃,反应时间10 h。在最佳反应条件下,聚合松香的软化点为139.4℃。EDS与反应物分离后可以重复使用,经过5次循环使用后催化剂活性未见明显的下降。

Effective conversion of fructose to 5-ethoxymethylfurfural with brønsted acid site(S/Cl)-functional carbon catalysts

Brønsted acid site(S/Cl)-functional carbon materials were prepared by ball-milling(bm)L-cysteine and ammonium chloride to form chemical complex solids,by post-heat treatment(Q)of the solids at 500°C under a nitrogen gas atmosphere to stabilize and fortify amino and functional group solid structures and by post-oxidative treatment with H_(2)O_(2)to add Brønsted acidity.The as-prepared carbon materials(S/Cl@bm_(x)Q_(y);x,y in hours)contained Brønsted acid sites(sul-fonates,chlorides),oxygen-containing groups(-COOH,-OH)and amino functional groups.The S/Cl@bm_(x)Q_(y)materials were applied as catalysts to promote conversion of fructose in ethanol solvent to 5-hydroxymethylfurfural(5-HMF)and 5-ethoxymethylfurfural(5-EMF).Among the carbon materials,S/Cl@bm_(3)Q_(1)gave 5-EMF and 5-HMF yields of 67.0%and 22.8%,respectively,in pure ethanol at 140℃for 24 h reaction time,while a reaction time of 18 h gave total 5-EMF and 5-HMF yields of 96.4%.Dimethyl sulfoxide(DMSO)was applied as additive to the ethanol-fructose-S/Cl@bm_(3)Q_(1)reaction system which showed that 5-HMF product selectivity could be controlled with DMSO concentration.The protocol developed allows simple preparation of func-tional carbon materials that have high catalytic activity and are effective for conversion of fructose to 5-HMF and 5-EMF in ethanol.

Designing a Bifunctional Brønsted Acid-Base Heterogeneous Catalyst Through Precise Installation of Ligands on Metal-Organic Frameworks

A Brønsted acid-base bifunctional metal-organic framework(MOF)catalyst,PCN-700-AB[A=Brønsted acid site,TPDC-(COOH)_(2)[(1,1′∶4′,1″-terphenyl)-2,2″,4,4″-tetracarboxylic acid]and B=Brønsted basic site,BDC-NH_(2)],was designed precisely and synthesized successfully through sequential installation of Brønsted acid and base functionalities in a crystalline zirconium(Zr)-MOF.The installation underwent single-crystal-to-singlecrystal transformation throughout the process;hence,the structure of the bifunctional catalyst could be characterized accurately via single-crystal X-ray crystallography.The bifunctional MOF catalyst obtained exhibited excellent acid-base catalytic activity for a cascade of one-pot deacetalization-Knoevenagel condensation reaction.The work presented here could be considered as a promising solution to incorporate multifunctional components readily,especially the hostile aspects,into one MOF structure.

Nickel-and Brønsted Acid-Catalyzed Redox-Neutral Coupling of 1,3-Dienes and Aldehydes for Synthesis of Dienols

Dienols are important structural motifs in organic molecules,but most of the traditional synthetic methods required multistep prefunctionalization of substrates,leading to stoichiometric waste and low atom economy.Herein,we report a redox-neutral coupling of simple 1,3-dienes and aldehydes via nickel and Brønsted acid dual catalysis,providing a highly atom-economical and by-product-free route to various dienols with up to 94%yield and up to 50∶1 EE/EZ ratio.The use of 2-isopropoxyphenol as a Brønsted acid co-catalyst was critical to the reactivity and selectivity.

Recyclable Cu Salt-Derived Brønsted Acids for Hydrolytic Hydrogenation of Cellulose on Ru Catalyst

Brønsted acid-catalyzed hydrolysis of cellulose,the most abundant source of biomass in nature,is the critical step for its depolymerization and subsequent conversion to sugar alcohols and other important chemicals.Mineral acids are highly active;however,the difficulties in recycling and disposal limit their practical applications.

Brønsted酸性离子液体催化Fries重排合成对羟基苯乙酮的研究

采用一步法合成了[PPh_(3)][TfOH]_(2)、[TNOA][TfOH]_(2)、[TNOA][TfOH]和[PPh_(3)][TfOH]共4种离子液体。通过红外探针法对离子液体的酸性类型与酸性强弱进行了表征;同时对离子液体催化Fries重排选择性合成对羟基苯乙酮的收率进行了条件优化。结果表明,当选择[PPh_(3)][TfOH]_(2)作催化剂兼溶剂时,在反应温度为60℃、n(乙酸苯酯)∶n(离子液体)为1∶2、反应时间为6 h的条件下,选择性生成对羟基苯乙酮最高收率达到75%;催化剂可循环利用5次不失活。通过1HNMR监测反应前后催化剂结构变化,推导了其可能的反应机理。

A high-surface-area silicoaluminophosphate material rich in Brnsted acid sites as a matrix in catalytic cracking

A transparent gel-like mesoporous silicoaluminophosphate material （SAP） with molar ratio of Si/Al = 20 was synthesized by hydrothermal method. The physicochemical features of SAP were characterized by XRD, XRF, BET, SEM and FT-IR spectroscopy of pyridine adsorption techniques. The results indicated that incorporation of phosphorus （P） into aluminasilica system altered the basic textural characteristics of aluminasilica. Especially after hydrothermal treatment, the material with large special surface area （up to 492 m2/g） exhibited a good performance on hydrothermal stability. Moreover, the phosphorus modifier can not only increase the amount of Br／＂{o}nsted acidic sites （up to 48.44 μmol/g） and the percentage of weak acidic sites in total acidic sites, but also regulate the acid type, such as the ratio of B/L （Lewis acid/Br？nsted acid） increased to 1.15. The performances of samples as matrices for the catalytic cracking of heavy VGO were investigated. At 520 ℃, the catalysts showed much higher gasoline and diesel oil yields achieving to 45.59 wt% and 19.20 wt%, respectively, and lower coke selectivity （2.86%） than conventional FCC matrices, such as kaolin and amorphous silica-alumina.

Transesterification of palm oil to biodiesel using Brφnsted acidic ionic liquid as high-efficient and eco-friendly catalyst

The transesterification of palm oil and methanol catalyzed by Br?nsted acidic ionic liquids was investigated. Four eco-friendly Br?nsted acidic ionic liquids were prepared and their structures were characterized by NMR, FT-IR and TG–DTG. The results demonstrated that [CyN_(1,1)PrSO_3H][p-TSA] was more efficient than the other ionic liquids and chosen as catalyst for further research. The influences of various reaction parameters on the conversion of palm oil to biodiesel were performed, and the orthogonal test was investigated to seek the optimum reaction conditions, which were illustrated as follows: methanol to oil mole ratio of 24:1, catalyst dosage of 3.0 wt% of oil, reaction temperature of 120 °C, reaction time of 150 min, and the biodiesel yield achieved 98.4%. In addition, kinetic study was established for the conversion process, with activation energy and preexponential factor of 122.93 k J·mol^(-1) and 1.83 × 10^(15), respectively. Meanwhile, seven-time recycling runs of ionic liquid were completed with ignorable loss of its catalyst activity. The refined biodiesel met the biodiesel standard EN 14214.

The alcoholysis of acetonitrile prompted by Brфnsted acidic ionic liquid [HSO_3-pmim]HSO_4

BrФnsted acidic ionic liquids based on imidazolium cation were employed as a series of environmentally benign catalysts and mediums in the alcoholysis of acetonitrile to synthesize ester. The results showed that BrФnsted acidic ionic liquid [HSO3- pmim]HSO4 was an efficient catalyst and medium for the alcoholysis of acetonitrile which could be recycled easily without obvious decline in catalytic activity, the highest yield could reach 85%.

Preparation of fructone catalyzed by water-soluble Brφnsted acid ionic liquids

Fructone （2-methyl-2-ethylacetoacetate-1, 3-dioxolane）, a flavouring material, has been synthesized from ethyl acetoacetate and glycol using five water-soluble Brφnsted acid ionic liquids as catalysts for the first time. The used Brφnsted acid ionic liquids include [Hmim]Tfa, [Hmim]Tsa, [Hmim]BF4, [Bmim]HSO4, [Bmim]H2P04, and [Hmim]BF4 showed the highest catalytic activity for the preparation of fructone. After reaction, the product could be isolated from the reaction system automatically, and the ionic liquid could be directly reused without dehydration.

Study on extraction of thiophene from model gasoline with brønsted acidic ionic liquids

Brønsted acidic ionic liquids(ILs),N-methylimidazole hydrogen sulfate([HMIm]HSO_(4))and N-methylpyrrolidone hydrogen sulfate([HNMP]HSO_(4)),are synthesized and employed as extractants to extract thiophene from model gasoline(thiophene dissolved in noctane).The effect of extraction temperature,extraction time and volume ratio of ILs to model gasoline on desulfurization rates is investigated.Then,the optimal desulfurization conditions are obtained:the ratio of ILs to model gasoline is 1∶1,extraction temperature is 50℃ for[HMIm]HSO_(4)and 60℃ for[HNMP]HSO_(4),extraction time is 60 min.Meanwhile,the desulfurization rate of[HNMP]HSO_(4)for model gasoline is 62.8%,which is higher than that of[HMIm]HSO_(4)(55.5%)under optimal conditions.The reason is discussed on the basis of the interaction energy between thiophene and ILs at the B3LYP/6-311++G(d,p)level.Furthermore,the total desulfurization rate of[HNMP]HSO_(4)and[HMIm]HSO_(4)reaches 96.4%and 94.4%,respectively,by multistage extraction.Finally,the used ILs can be reused by vacuum drying,and their desulfurization rates are not significantly decreased after recycling 7 times in single-stage desulfurization.

Novel Brфnsted Acidic Ionic Liquid Based on a Cyclic Guanidinium Cation:a Green,Efficient,and Recyclable Dual Slovent-catalyst System for Fisher Esterification

A novel BrФnsted acidic ionic liquid（IL） based on the cyclic guanidinium cation has been synthesized. This IL, as a strong BrФnsted acid catalyst or solvent, shows high catalytic activity and biphsaic behavor in the esterifications of carboxylic acids and alcohols. The produced esters as a separate phase can be conveniently decanted out from the IL and the IL is recyclable without any loss of catalytic activity.

Surface BrØnsted-Lewis dual acid sites for high-efficiency dinitrogen photofixation in pure water

As is known to all, nitrogen not only plays an important role in the industrial development of human society but also plays an important part in the proteins that constitute the essence of life[1]. In 1910, the Haber-Bosch process was first used to synthesize ammonia.

Brφnsted酸功能化离子液体催化环己醇脱水制备环己烯

BrФnsted酸离子液体可催化烷基化、酯化、醚化、缩合、重排等反应，为了降低离子液体的成本及筛选新的离子液体催化剂，设计合成了BrФnsted酸功能化离子液体眠N，N-三甲基-N-磺丙基-硫酸氢铵（TMPSHS04），其结构经IR，^1HNMR，^13CNMR和MS的确证。以TMPSHSO4作为催化剂，对环己醇脱水制备环己烯的反应进行了研究。最佳反应条件为m（催化剂）：m（环己醇）=1：50，反应时间2h，反应温度170～180℃，产品收率达87．2％，GC／MS分析结果表明，产品质量分数达99．04％，产品选择性为99．3％，离子液体可以回收并重复使用，催化活性保持不变。

Brφnsted酸性功能化双核离子液体制备及催化合成醋酸丁酯研究

采用两步法制备了功能化Brφnsted酸性双核咪唑离子液体催化剂,并用1H-NMR、FT-IR对催化剂的结构进行了表征,系统考察了其在醋酸与丁酯催化酯化高选择性地合成醋酸丁酯反应中的催化性能。结果表明,功能化Brφnsted酸性双核咪唑离子液体具有很好的催化活性,其催化活性与阴离子的种类有关,其中双-(3-甲基-1-咪唑)亚丁基双硫酸氢盐(MTEIMHS)的催化活性最好,在最佳催化剂用量为1.6%(wt),反应在90℃的温度下反应4 h,醋酸转化率可达到82%,且选择性接近99.9%。由此可见MTEIMHS双核离子液体有望成为一种有潜力的酯化催化剂。

Beta分子筛中Al的分布和Brφnsted酸的酸性强度

基于量子化学中的密度泛函理论(DFT),研究了Beta分子筛中骨架Al在9个不同T位的分布和Brφnsted酸的分布及其强度.计算采用8T簇模型和B3LYP/6-31G(d,p)方法,得到了不同T位的Al/Si替代能、(Al,H)/Si替代能和质子亲和势,以及碱性探针分子NH3在Beta分子筛酸性位的吸附能.结果表明,骨架Al和Brφnsted酸优生位于Beta分子筛的T5和T6位;其中酸性最强的位置是Al5-O14-Si9,最弱的位置是Al7-O3-Si1.

Brφnsted酸性离子液体中芳烃硝化反应的研究

以BrФnsted酸性离子液体[Hmim][CF3COO]（三氟乙酸根甲基眯唑盐）和[Hmim][HSO4]（硫酸氢根甲基咪唑盐）作为溶剂和催化剂，硝酸铵为硝化剂，研究了烷基苯和卤苯等芳香化合物的硝化反应。在0℃到室温的硝化条件下，烷基苯和卤苯都能被硝化成-硝基化合物，收率为40％-80％。甲苯等烷基苯的硝化选择性与硝硫混酸中的硝化选择性相当；卤苯硝化的对位选择性则远高于硝硫混酸中的硝化结果。其中氯苯在18℃下反应8h，三氟乙酸酐（TFAA）／硝酸铵为4时产物的对邻比达到6．2，而溴苯在0℃下反应8h，TFAA／硝酸铵为5时产物的对邻比可达到14．0，并且生成的对硝基溴苯可以从反应液中析出，得到对硝基溴苯含量为98％的产物。

Brφnsted酸离子液体催化合成N-叔丁基丙烯酰胺

合成并表征了Brφnsted酸离子液体,用于催化Ritter反应合成N-叔丁基丙烯酰胺。通过Hammett函数法测定了离子液体的酸度函数值。通过考察各种离子液体的催化活性及重复使用性能,选定Brφnsted酸离子液体[EPy][HSO4]为催化合成N-叔丁基丙烯酰胺,研究了反应时间、反应温度等因素对酰化反应的影响,同时考察了离子液体的循环使用性能。得到其较佳工艺条件:反应温度50℃,反应时间6h,收率达到85.6%。分离后的离子液体经真空干燥后重复使用5次,催化活性基本不变。