A step‐growth strategy to grow vertical porous aromatic framework nanosheets on graphene oxide:Hybrid material‐confined Co for ammonia borane methanolysis

The rational synthesis of a two-dimensional(2D)porous aromatic framework(PAF)with a controllable growth direction remains a challenge to overcome the limitation of traditional stacked 2D materials.Herein,a step-growth strategy is developed to fabricate a vertically oriented nitrogen-rich porous aromatic framework on graphene oxide(V-PAF-GO)using monolayer benzidine-functionalized GO(BZ-GO)as a molecular pillar.Then,the confined Co nanoparticle(NP)catalysts are synthesized by encapsulating ultra-small Co into the slit pores of V-PAF-GO.Due to the high nitrogen content,large specific surface area,and adequate slit pores,the optimized vertical nanocomposites V-PAF-GO provide abundant anchoring sites for metal NPs,leading to ultrafine Co NPs(1.4 nm).The resultant Co/V-PAF-GO catalyst shows an extraordinary catalytic activity for ammonia borane(AB)methanolysis,yielding a turnover frequency value of 47.6 min−1 at 25°C,comparable to the most effective non-noble-metal catalysts ever reported for AB methanolysis.Experimental and density functional theory studies demonstrate that the electron-donating effect of N species of PAF positively corresponds to the low barrier in methanol molecule activation,and the cleavage of the O–H bond in CH3OH has been proven to be the rate-determining step for AB methanolysis.This work presents a versatile step-growth strategy to prepare a vertically oriented PAF on GO to solve the stacking problem of 2D materials,which will be used to fabricate other novel 2D or 2D–2D materials with controllable orientation for various applications.

Methanolysis of amides under high-temperature and high-pressure conditions with a continuous tubular reactor

The methanolysis of amides,which is widely employed in the synthetic organic chemistry,hardly occurs under mild conditions.To safely and controllably intensify the methanolysis reaction with hightemperature and high-pressure environment,a continuous tubular reaction technology is developed,whose space-time yield is over twice of that of the conventional batch reaction.The methanolysis of acetanilide is selected as the representative reaction,and the influences of temperature,pressure,reactant and catalyst concentration,and residence time on the reaction performances are systematically investigated.Taking the advantages of precise temperature and reaction time control by the tubular reactor,the kinetics of acetanilide methanolysis are determined and compared to the kinetics of acetanilide hydrolysis reaction.The tubular reaction method is also employed to test a variety of other amides to show the effects of substituents,steric hindrance,and alkalinity on the reaction rate of methanolysis.

Hydrogen generation from methanolysis of sodium borohydride over Co/Al_2O_3 catalyst

Co/Al2O3 catalyst is prepared with an impregnation-chemical reduction method and used to catalyze the methanolysis of sodium borohydride （NaBH 4） for hydrogen generation.At solution temperature of 0 C,the methanolysis reaction can be effectively accelerated using Co/Al2O3 catalyst and provide a desirable hydrogen generation rate,which makes it suitable for applications under the circumstance of low environmental temperature.The byproduct of methanolysis reaction is analyzed by X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FTIR）.The characterization results indicate that methanol can be easily recovered after methanolysis reaction by hydrolysis of the methanolysis byproduct,NaB（OCH 3） 4.The catalytic activity of Co/Al2O3 towards NaBH 4 methanolysis can be further improved by appropriate calcination treatment.The catalytic methanolysis kinetics and catalyst reusability are also studied over the Co/Al2O3 catalyst calcined at the optimized temperature.

STUDY ON METHANOLYSIS STABILITY OF OPTICALLY ACTIVE COPOLYMERS OF TRIPHENYLMETHYL METHACRYLATE AND METHYL METHACRYLATE

The methanolysis of poly(triphenylmethyl methacrylate) (PTrMA) and its copolymers P(TrMA-co-MMA), P(TrMA-b-MMA) has been studied in the presence of anhydrous methanol at 40 degrees C by electroconductometric method. It has been found that the methanolysis stability can be obviously improved for the copolymer, especially, the radom copolymer, P(TrMA-co-MMA).

Carbohydrate analysis by methanolysis method and application to compositional analysis of transparent exopolymer particles

Measurement of uronic acids (URAs) which are a group of acidic sugar, would be useful for the understanding of dynamics of bacterial extracellular polymeric substances (EPS) in marine environments. However, the URA analysis using traditional hydrolysis method which is used for neutral sugar analysis poses serious problems in URA that is unstable under hydrolysis. We developed the methanolysis method, which deploymerizes polysaccharides while retaining quantitative information. Our method was applied to coastal seawater, and the URAs distribution was compared with that of transparent exopolymer particles (TEP) which are acidic sugar containing particles. Since the relationship of URA with TEP was relatively weak, URA-containing polysaccharides present in bacterial EPS would not participate as a structural component of TEP.

Methanolysis of Mixed Crop Oils (<i>Hevea brasiliensis</i>and <i>Jatropha curcas</i>L.) into Biodiesel: Kinetics Study

In this study, the methanolysis of mixed crop oils (Hevea brasiliensis and Jatropha curcas L.) was investigated. Due to the oils contain high impurities, a particular pre-treatment of which was carried out. For alkali-catalyzed methanolysis, few parameters (such as: molar ratio, catalyst percentage, and reaction time) were studied. The results showed that the methanolysis optimum conditions were 5.5 of molar ratio, 0.9% w/w of catalyst, and 60 minutes of reaction time with the highest yield of 98.9%. The kinetics study indicated that first order reaction mechanism with reaction rate constant and activation energy were 1.5 × 10-2 minute-1 and 23.93 KJ?mol-1 respectively. As fuel, the physicochemical properties of biodiesel met the standard values required by ASTM D6751.

Concentration of n-3 polyunsaturated fatty acid glycerides by Candida antarctica lipase A-catalyzed selective methanolysis

n-3 polyunsaturated fatty acids(n-3 PUFA)have biologically important functions in human beings,but their contents in natural oils are usually low.This study investigated the concentration of n-3 PUFA-enriched glycerides by Candida antarctica lipase A(CAL-A)-catalyzed selective methanolysis of algal oil.First,lipases and acyl acceptors were screened.Subsequently,the methanolysis conditions including methanol concentration in aqueous solution,molar ratio of methanol to oil,reaction temperature,lipase loading and reaction time,were optimized.The results indicated that CAL-A could effectively identify n-3 PUFA during methanolysis.Saturated fatty acids and monounsaturated fatty acids were released from algal oil by CAL-A-catalyzed methanolysis,causing the production of n-3 PUFA-enriched glycerides.Under optimal conditions(3:1 of molar ratio of methanol to algal oil,20%methanol aqueous solution,6%CAL-A dosage,25℃,18 h),the n-3 PUFA content increased from the initial 45.96%to 73.96%,with an n-3 PUFA yield of 81.76%.The reusability of CAL-A demonstrated that under optimal conditions the lipase could be used for 8 times.Therefore,this enzymatic process is efficient for synthesis of n-3 PUFA-enriched glycerides.

Enzymatic Synthesis of Fatty Acid Methyl Esters from Crude Rice Bran Oil with Immobilized Candida sp. 99-125

The non-edible crude rice bran oil was extracted from white rice bran, and then was catalyzed by immobilized lipase for biodiesel production in this study. The effects of water content, oil/methanol molar ratio, temperature, enzyme amount, solvent,number of methanol added times and two-step methanolysis by using Candida sp. 99-125 as catalyst were investigated. The optimal conditions for processing 1 g rice bran oil were: 0.2 g immobilized lipase, 2 ml n-hexane as solvent, 20% water based on the rice bran oil mass, temperature of 40 °C and two-step addition of methanol. As a result, the fatty acid methyl esters yield was 87.4%. The immobilized lipase was proved to be stable when it was used repeatedly for 7 cycles.

Effective production of γ-valerolactone from biomass-derived methyl levulinate over CuO_x-CaCO_3 catalyst

The production of?-valerolactone(GVL)from lignocellulosic biomass has become a focus of research owing to its potential applications in fuels and chemicals.In this study,(n)CuOx-CaCO3(where n is the molar ratio of Cu to Ca)compounds were prepared for the first time and shown to function as efficient bifunctional catalysts for the conversion of biomass-derived methyl levulinate(ML)into GVL,using methanol as the in-situ hydrogen source.Among the catalysts with varied Cu/Ca molar ratios,(3/2)CuOx-CaCO3 provided the highest GVL yield of 95.6% from ML.The incorporation of CaCO3 with CuO resulted in the formation of Cu+species in a CuOx-CaCO3 catalyst,which greatly facilitated the hydrogenation of ML.Notably,CuOx-CaCO3 also displayed excellent catalytic performance in the methanolysis products of cellulose,even in the presence of humins.Therefore,a facile two-step strategy for the production of GVL from cellulose could be developed over this robust and inexpensive catalyst,through the integration of cellulose methanolysis catalyzed by sulfuric acid,methanol reforming,and ML hydrogenation in methanol medium.

Biodiesel synthesis via metal oxides and metal chlorides catalysis from marine alga Melanothamnus afaqhusainii

This research article demonstrates the most comprehensive comparative catalytic study of different metal oxides and metal chlorides towards the methanolysis of triglycerides of marine red macroalga Melanothamnus alhqhusainii. CaO was found to be the most reactive metal oxide that yielded 80% biodiesel while ZnCI2 was the most reactive metal chloride that produced 60% biodiesel by mechanical stirring for 6 h at 100-110 ℃. The overall reactivity order of the catalysts was found to be CaO 〉 MgO 〉 Pb02 〉 ZnC12 〉 TIC14 〉 PbO 〉 HgC12 〉 ZnO 〉 AIC13 〉 SnCI2 〉 TiO2 whereas, CaCI2, MgCI2, A1203, HgO, PbCI2, MnO2, MnC12, Fe203 and FeCI3 were found to be non-reactive for transesterification of triglycerides. In addition, a detailed study of the screening of mobile phases and spraying reagents was conducted which showed that petroleum ether ： chloroform ： toluene （7：2：1 ） is the best mobile phase, whereas iodine crystals/silica gel is the best visualizing agent for the thin layer chroma- tography （TLC） examination ofbiodiesel. Biodiesel production was confirmed by comparative TLC examination. It was further supported by the determination of fuel properties of biodiesel, which were found to be similar to the standard limits of American Society for Testing and Materials （ASTM）,

A review on hydrogen production from ammonia borane:Experimental and theoretical studies

Ammonia borane(NHsBH3,AB)is an ideal raw material of hydrogen production with higher hydrogen storage capacity.In this paper,the catalytic processes of AB dehydrogenation were described from different ways,including thermal dehydrogenation,hydrolysis,methanolysis,photocatalysis and photopiezoelectric synergy catalysis with experimental research and theoretical calculations.Catalyst models include bulk materials,two-dimensional materials,nanocluster particles and single/diatomic structures.Among them,the proportion of H2 released is different,and the reaction conditions are also different,which are suitable for different application scenarios.Through this review,we could have a preliminary comprehensive understanding of AB dehydrogenation reaction.

Non-equilibrium model for catalytic distillation process

A new improved tri-diagonal method was developed for the non-equilibrium stage model of the catalytic distillation by coupling consumptive reaction coefficient.The reactions in the distillation column were divided into generative reaction and consumptive reac-tion.The non-equilibrium stage model was introduced for the catalytic distillation process of the dimethyl car-bonate(DMC)synthesis by urea methanolysis over solid based catalyst,and the improved tri-diagonal method was used to solve the model equations.Comparison of pre-dicted results with experiment data shows that the mean relative error of the yield of DMC was 3.78%under dif-ferent conditions such as different operating pressures and reaction temperatures.The improved tri-diagonal matrix method could avoid the negative values of the liquid com-positions during the calculations and restrain the fluc-tuation of compositions by slowing down the variations of the values in the iteration.The modeling results show that the improved tri-diagonal method was appropriate for system containing a wide range of boiling point com-ponents and a different rate of reactions.

Synthesis and crystal structure of nickel(Ⅱ) and zinc(Ⅱ) complexes with 2,4-bis(3,5-dimethylpyrazol-l-yl)-6-methoxyl-1,3,5-triazine

2,4-Bis(3,5-dimethylpyrazol-1-yl)-6-methoxyl-1,3,5-triazine(bpt) has been synthesized by using a new, simple and general method with high yields. Reactions of bpt with Ni(ClO4)2·6H2O and Zn(ClO4)2·6H2O in methanol gave mononuclear complex [Ni(bpt)2]· (ClO4)2·H2O and ternary complex [Zn(mpt)2(dmp)](ClO4)2 respectively, where mpt (2,4-dimethoxy-6-(3,5-dimethyl- pyrazol-1-yl)-1,3,5-triazine) and dmp(3,5-dimethylpyrazole) are the alcoholysis products of bpt in the presence of Zn2+ ion. A possible mechanism for this catalytic reaction was proposed. X-ray crystal structure for ligand bpt, Ni and Zn complexes are reported. The protonated form of the ligand bpt crystallizes as its perchlorate salt including one molecule of water, [Hbpt·H2O·ClO4]. The proton is located on one pyrazole N-atom. [Hbpt·H2O·ClO4], in which [Hbpt]+ is in cis-cis conformation, are packed in slipped stacks of approximately parallel layers. The Π -Π overlap interactions between the non-protonized pyrazoles of the adjacent layers give a zigzag arrangement of the planar aromatic [Hbpt]+ molecules. In [Ni(bpt)2](ClO4)2·H2O, bpt are meridionally three-coordinated with Ni2+. The coordination sphere around Ni2+ is a slightly distorted square bipyramid, where four pyrazole nitrogen atoms occupy the basal positions and two triazine nitrogen atoms the apical one. In [Zn(mpt)2(dmp)](ClO4)2, the Zn atom is coordinated with a pair of bidentate mpt ligands and one monodentate dmp ligand, forming a distorted trigonal bipyramid, where the two triazine nitrogen atoms of mpt and one nitrogen atom of dmp occupy the basal positions, and the two pyrazole nitrogen atoms of mpt the apical one.