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.

Reductive amination of aldehydes and ketones using sodium borohydride in the presence of silica chloride under solvent-free conditions

A simple and convenient procedure for the preparation of amines from aldehydes and ketones with sodium borohydride activated by silica chloride as a catalyst under solvent-free conditions is described.A variety of aliphatic and aromatic aldehydes,ketones and amines when mixed with NaBH;/silica chloride at room temperature,afforded excellent yield of the corresponding amines.

Oxalic Acid Promoted Hydrolysis of Sodium Borohydride for Transition Metal Free Hydrogen Generation

We reported an inexpensive and high-efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt%based on all the reactants can be achieved with excellent hydrogen generation kinetics.

The Unexpected Reductive Products of δ-Alkoxyenal by Sodium Borohydride in Methanol with A Trace of Magnesium Methoxide

Reduction of d-alkoxy enal 1 and 4 by sodium borohydride in methanol with a catalytic amount of magnesium methoxide gave unexpected methoxylated poducts 3 and 6 respectively.

Oxalic Acid Promoted Hydrolysis of Sodium Borohydride for Transition Metal Free Hydrogen Generation

We reported a low cost,high efficiency hydrogen generation method from NaBH4 hydrolysis promoted by oxalic acid.NaBH4 and H2C2O4 were premixed and hydrogen generation was initiated by adding water into the solid mixture.H2C2O4 was selected as the acid promotor due to its solid state and low mass per proton.The effect of reactant ratio on the hydrogen yield and hydrogen storage density was investigated.With optimized reactant ratio,high gravimetric hydrogen storage up to 4.4wt% based on all the reactants can be achieved with excellent hydrogen generation kinetics.

THE UNUSUAL REDUCTION OF SOME AROMATIC ALDEHYDES BY SODIUM BOROHYDRIDE

Two aromatic aldehydes are found to be reduced by an unusual way by sodium borohydride in the presence of water to yield the corresponding methyl substituted aryl compounds.

Chemoselective Reduction of Fenofibric Acid to Alcohol in the Presence of Ketone by Mixed Anhydride and Sodium Borohydride

A highly efficient and facile protocol for the selective reduction of carboxylic acid of Fenofibric acid to corresponding alcohol was developed. The selective reduction was carried out by activation of carboxylic acid by mixed anhydride followed by the reaction of sodium borohydride in presence of methanol. This is the first example of chemoselective reduction of carboxylic acid to alcohol in presence of a ketone without any external catalyst or ligand in a single step. The reaction offers wide applicability for the selective carboxylic group reduction methodology. The chemoselective reduction was demonstrated by the reduction of Fenofibric acid, an active metabolite of the drug Fenofibrate, to corresponding alcohol in excellent selectivity, yield, and purity.

TELLURIUM-CATALYZED DEPROTECTI ON OF ARYL CHLOROACTATES BY SODIUM BOROHYDRIDE

In the presence of catalytic amounts of tellurium,aryl chloro- acetates can be cleaved by sodium borohydride and regenerate parent phen- ols in good yields.

Direct oxidation of methane at low temperature using Pt/C,Pd/C,Pt/C-ATO and Pd/C-ATO electrocatalysts prepared by sodium borohydride reduction process

The main objective of this paper was to characterize the voltammetric profiles of the Pt/C,Pt/C-ATO,Pd/C and Pd/CATO electrocatalysts and study their catalytic activities for methane oxidation in an acidic electrolyte at 25 ℃ and in a direct methane proton exchange membrane fuel cell at 80 ℃. The electrocatalysts prepared also were characterized by X-ray diffraction( XRD) and transmission electron microscopy( TEM). The diffractograms of the Pt/C and Pt/C-ATO electrocatalysts show four peaks associated with Pt face-centered cubic( fcc) structure,and the diffractograms of Pd/C and Pd/C-ATO show four peaks associated with Pd face-centered cubic( fcc) structure. For Pt/C-ATO and Pd/C-ATO,characteristic peaks of cassiterite( SnO_2) phase are observed,which are associated with Sb-doped SnO_2( ATO) used as supports for electrocatalysts. Cyclic voltammograms( CV) of all electrocatalysts after adsorption of methane show that there is a current increase during the anodic scan. However,this effect is more pronounced for Pt/C-ATO and Pd/C-ATO. This process is related to the oxidation of the adsorbed species through the bifunctional mechanism,where ATO provides oxygenated species for the oxidation of CO or HCO intermediates adsorbed in Pt or Pd sites. From in situ ATR-FTIR( Attenuated Total Reflectance-Fourier Transform Infrared) experiments for all electrocatalysts prepared the formation of HCO or CO intermediates are observed,which indicates the production of carbon dioxide. Polarization curves at 80 ℃in a direct methane fuel cell( DMEFC) show that Pd/C and Pt/C electroacatalysts have superior performance to Pd/C-ATO and Pt/C-ATO in methane oxidation.

Study on catalyst for the sodium borohydride hydrolysis

The effects of preparation methods, supports and active parts on both the activation and stability of catalyst for the sodium borohydride hydrolysis were studied, and the results showed that the activation and stability of the catalysts prepared by impregnation method is better than that prepared by chemical plating. Compared to exchange resin and activated alumina, the diatomite with high BET surface area and porosity is more suitable for as the catalyst’s support. Co is much better than Ni when used as catalytic active part.

Ultrafast room-temperature reduction of graphene oxide by sodium borohydride,sodium molybdate and hydrochloric acid

Since graphene-based materials have shown great potential in many fields,it is important to explore ultrafast and high-efficient methods to synthesize reduced graphene oxide(rGO) using inexpensive reducing agents under mild conditions.Here,we reported a novel method for the ultrafast chemical reduction of graphene oxide(GO) at room temperature using sodium borohydride(NaBH_(4)),sodium molybdate(Na_(2)MoO_(4)) and hydrochloric acid(HCl).The reduction was carried out within 2 min.A series of characterization results revealed that the obtained reduced graphene oxide has higher reduction degree than that synthesized by NaBH_(4) alone at high temperature.Moreover,rGO electrode based on the present reducing method exhibited a superior specific capacitance of 139.8 F/g at a current density of1 A/g,indicating that it can be used as electrode materials for supercapacitors.

Cotton stalk activated carbon-supported Co-Ce-B nanoparticles as efficient catalysts for hydrogen generation through hydrolysis of sodium borohydride

Porous cotton stalk activated carbons(CSAC)were prepared by phosphoric acid activation of cotton stalks in a fluidized bed.The CSAC-supported Co-B and Co-Ce-B catalysts were prepared by the impregnation-chemical reduction method.The samples were characterized by the nitrogen adsorption,XRD,FTIR and TEM measurements.The effects of the sodium borohydride(NaBH_(4))and sodium hydroxide(NaOH)concentrations,reaction temperature and recyclability on the rate of NaBH_(4)hydrolysis over the CSAC-supported Co-Ce-B catalysts were systematically investigated.The results showed that the agglomeration of the Co-Ce-B nanoclusters on the CSAC support surface was significantly reduced with the introduction of cerium.The CSAC-supported Co-Ce-B catalyst exhibited superior catalytic activity and the average hydrogen generation rate was 16.42 L min^(−1)g^(−1)Co at 25℃,which is higher than the most reported cobalt-based catalysts.The catalytic hydrolysis of NaBH_(4)was zero order with respect to the NaBH_(4)concentration,and the hydrogen generation rate decreased with the increase in the NaOH concentration.The activation energy of the hydrogen generation reaction on the prepared catalyst was estimated to be 48.22 kJ mol^(−1).A kinetic rate equation was also proposed.

The mechanism of unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to l,2,3,4-tetrahydrofuro[3,4-b]-pyridin-5(7H)-one with sodium borohydride

An unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to 1,2,3,4-tetrahydrofuro[3,4-b]pyridin-5（7H）-one with sodium borohydride in ethanol and tetrahydrofuran, respectively, is described, a hypothetic mechanism for the unusual reductive product is proposed.

Cobalt,a reactive metal in releasing hydrogen from sodium borohydride by hydrolysis:A short review and a research perspective

Cobalt is commonly admitted as being a promising catalyst in accelerating NaBH4 hydrolysis,being as reactive as noble metals and much more cost-effective.This is the topic of the present paper.Herein,we survey(i) the NaBH4-devoted literature while especially focusing on the Co catalysts and(ii) our work on the same topic.Finally,we report(iii) reactivity results of newly developed Co-based catalysts.From both surveys,it mainly stands out that Co has been investigated as catalysts in various forms:namely,as chlorides,reduced nanoparticles(metal Co,Co boride,Co-B alloy),supported over supports and shaped.In doing so the reactivity can be easily varied achieving H2 generation rates from few to 】1000 L(H2)/min·g(metal).Nevertheless,our work can be distinguished from the NaBH4 literature.Indeed,we are working on strategies that focus on making alternative Co-based catalysts.One of these strategies is illustrated here as we report new reactivity data of Co-based bimetallic supported catalysts.For example,we show that 20 wt% Co90Y10/γAl2O3-20 wt% Co95Hf5/γAl2O3 】 20 wt% Co99Zr1/γAl2O3 】 20 wt% Co/γAl2O3,the best catalysts showing HGRs of about 245 mL(H2)/min or 123 L(H2) /min·g(metals).

Co-MOF衍生钴基催化剂制备及其NaBH_(4)水解制氢性能

采用钴基MOF为前驱体,通过惰性气氛碳化法制备了系列衍生钴基催化剂,探讨了不同催化剂在NaBH_(4)水解制氢中的催化性能.采用X射线衍射仪(XRD),透射电子显微镜(TEM),X射线光电子能谱分析(XPS),热重分析(TGA)等深度分析了不同碳化条件对Co-MOF衍生钴基催化剂的晶相结构、微观形貌、元素价态等的影响.研究结果表明:在不同碳化温度下,Co-MOF衍生钴基催化剂展示了不同的微观形貌、晶相结构和元素价态,随着惰性碳化温度升高节点钴逐步从离子钴向单质钴转化.NaBH4水解制氢实验表明不同碳化温度可以显著影响催化剂的水解制氢催化活性和稳定性,其中以钴离子转化的Co-MOF(300)催化剂展示了最佳催化活性,明显高于高温碳化的钴基催化剂.

Sn掺杂CoB催化剂的制备及其NaBH_(4)水解制氢催化性能

利用液相共还原法制备了一种Sn掺杂的Co-Sn-B非晶催化剂,研究该催化剂在NaBH4水解制氢中的催化活性。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等分析了Sn掺杂对Co-Sn-B催化剂微观结构、表面形貌、元素价态等的影响。结果表明,Sn掺杂摩尔比低于5.0%时,Co-Sn-B催化剂保持了良好的非晶态结构,Sn的引入可以显著提高催化剂的分散度并能有效抑制粒子团聚。NaBH4水解制氢实验表明,过渡金属Sn掺杂比例可以显著影响催化剂的水解制氢催化活性,当Sn掺杂比例为1.0%时,Co-Sn-B催化剂展示出最佳催化活性,同时其稳定性也明显高于未经Sn掺杂的CoB催化剂。

三种温和还原法制备Pt/SDB

Pt/SDB是液相催化交换(LPCE)反应处理核电产生含氚废水的一种很有前途的催化剂。采用悬浮聚合法制备得到介孔聚苯乙烯-二乙烯基苯(SDB),以硼氢化钠(SBH)、水合肼(HH)或乙二醇(EG)为还原剂,温和还原法制备SDB载体负载铂活性颗粒,产物分别记为Pt/SDB-SBH、Pt/SDB-HH或Pt/SDB-EG。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、氮气吸附脱附和氢-水催化交换实验等对其结构形貌及催化活性表征。结果表明:Pt/SDB-SBH疏水催化剂具有突出的性能和优异的催化活性,Pt纳米颗粒平均粒径约为3.3 nm,Pt^(0)组分比例为72.0%,催化交换柱效率达65.0%,并在120 min保持稳定。为低温还原制备Pt/SDB疏水催化剂提供了一种新的策略。

基于硼氢化钠原位还原的纳米金杂化酶的制备及催化阿魏酸甘油酯合成

建立了一种基于硼氢化钠原位还原法制备纳米金杂化酶用以合成阿魏酸甘油酯的方法,使杂化酶的催化活性、稳定性及结构的刚性皆有所提高.利用硼氢化钠原位还原法制备了NaBH_(4)@AuNPs-CRL杂化酶,通过单因素实验得到了最优的杂化条件,并利用荧光光谱、红外光谱、X-射线电子能谱、透射电镜等方法探究了杂化前后酶结构的变化.研究表明制备的NaBH_(4)@AuNPs-CRL杂化酶蛋白二级结构中α-螺旋含量减少、β-折叠含量增加,杂化酶比活性为4.91±0.12 U∙mg^(-1),与游离酶相比提高了66.44%,最佳条件下催化合成阿魏酸甘油酯的转化率为98.39%±3.65%,批式操作稳定性实验表明杂化酶的稳定性有较大提升.

掺杂型三维多孔纳米镍催化偶氮染料脱色性能

偶氮染料是纺织印染工业废水中的主要污染物,其大量排放会严重危害生物健康。为了开发一类有效的纳米催化剂对废水中的偶氮染料进行脱色,本文采用简单的水热合成法将Fe、Co元素掺杂到镍纳米材料中形成了具有三维网状多孔结构的三元金属纳米材料(Fe-Co-Ni NPs)。所制备的三元合金纳米材料为三维网状结构,少量的Fe、Co元素掺杂获得了更高的饱和磁化率,而未改变镍的多晶结构。在硼氢化钠存在条件下,由于多种金属元素之间的相互作用,Fe-Co-Ni NPs对刚果红的还原降解具有非常高的催化活性,2 min即可完全脱色,表观速率常数为1.24 min^(−1),明显优于二元Fe-Ni(1.00 min^(−1))、Co-Ni(0.96 min^(−1))及单金属Ni(0.83 min^(−1))纳米晶。Fe-Co-Ni NPs对其它偶氮染料甲基橙、直接红80及硝基苯酚类物质的还原降解也表现出较佳的催化性能。总之,该三元金属催化剂易于合成、成本低,对偶氮染料脱色效果好、稳定性高且可重复使用,非常适合工业偶氮废水的前期脱色处理。

等离子体Ag/TiO_(2-x)光阳极用于光电催化分解水

环境污染和破坏以及缺乏足够的清洁能源是目前全球范围内面临的严重的问题。半导体光催化材料因其可以利用太阳能且催化效率高等优点受到广泛关注,是当前研究的热点。二氧化钛(TiO_(2))具有良好的化学稳定性和环境兼容性,是传统半导体光催化材料之一。然而,其仍存在如催化活性易受光生载流子复合的影响及对太阳光的利用率低等缺陷。为了改善TiO_(2)的光电催化性能,使用硼氢化钠(NaBH4)氢化处理以及复合等离子体金属银(Ag)纳米粒子的方法制备得到Ag/TiO_(2)-x异质结构。借助SEM、TEM、XRD、XPS和固体紫外—可见漫反射测试手段对样品的形貌、结构、组成、表面元素以及光吸收性能进行表征。通过光电流密度、电化学阻抗谱以及光电转换效率(IPCE)对样品的光电活性进行测试,结果表明,Ag/TiO_(2-x)异质结构的光电流密度约为TiO_(2)的5倍,且具有较小的阻抗以及较高的IPCE活性。因此,富缺陷TiO_(2)-x和等离子体金属Ag纳米粒子的协同作用能促进其光电催化性能的提升。