Inexpensive Heterogeneous Catalyst Research Articles

The importance of cobalt disulfide morphology for cellulose depolymerization: Hydrogenolysis versus acid catalysis

Acid-catalyzed hydrolysis and metal-catalyzed hydrogenolysis are two important methods for conversion of cellulose into high value-added chemicals, which preferentially use homogeneous acids and precious metals as catalysts, respectively. This paper reports that cobalt disulfide (CoS2) can be competent in both acid hydrolysis and hydrogenolysis reactions as an inexpensive heterogeneous catalyst by controlling its morphology. Two kinds of CoS2 with imperfect spherical (A-CoS2) and regular octahedral (Syn-CoS2) morphologies were tested in the conversion of 5-hydroxymethylfurfural (HMF) under a hydrogen atmosphere. Interestingly, A-CoS2 showed high activity in the hydrogenolysis of HMF to 2,5-hexanedione (2,5-HD) with a yield of 81.5 wt%, while Syn-CoS2 was responsible for the acid hydrolysis of HMF to methyl levulinate (ML) in high yield of 90.8 wt%. Characterization of the two catalysts suggested that Syn-CoS2 had higher Co2+/Co3+ ratio in comparison to A-CoS2, leading to a proportional difference in their acid site numbers. The unique activity of these two catalysts was also reflected in the conversion of cellulose. In particular, Syn-CoS2 exhibited high selectivity to ML formation from cellulose and good recyclability.

Catalytic hydrothermal liquefaction of sewage sludge: Effect of metal support heterogeneous catalysts on products distribution

Industrial wastes and natural mixed oxide materials were evaluated as inexpensive heterogeneous catalysts supports for catalytic hydrothermal liquefaction (HTL) of biomass. In this study, Palygorskite (ATP) clay, a hydrated magnesium aluminosilicate clay mineral supported metal catalysts (Co, Mo and Co–Mo/ATP) and Al2O3 supported (Co, Mo, Co–Mo/Al2O3) catalysts were examined for the sewage sludge (SS) hydrothermal liquefaction (HTL). The highest biocrude yield of 34.2 wt% was obtained with Co–Mo/ATP bimetal catalyst. Biocrude characterization revealed that significantly different families of molecules were formed in the presence and absence of catalysts, implying that the main role of the catalyst is to promote rates of thermal reactions, leading to biocrude production. The improved catalytic HTL performance with Co–Mo metal catalyst as attributed to the synergistic effects of both metal sites present on catalyst surfaces. The main components of bio-oil were phenols, N-containing compounds and hydrocarbons, and the increased selectivity to hydrocarbons with Co–Mo/ATP was observed. Maximum yield of aromatic hydrocarbon (20% observed in case of HTL with metal supported ATP catalyst. presence of Co–Mo metal catalysts promoted the deoxygenating by reduction of oxygen in the form of carbon dioxide or water. The distribution of biocrude samples indicates that most compounds in biocrude were light-weighted and had low boiling points. There were more light-weight compounds in biocrude by adding catalyst.

Rational engineering of single-component heterogeneous catalysts based on abundant metal centers for the mild conversion of pure and impure CO2 to cyclic carbonates

• Novel, inexpensive heterogeneous catalysts for cyclic carbonate synthesis were prepared by readily accessible strategies. • The catalysts enabled the cocatalyst-free cycloaddition of CO 2 to several epoxides under mild conditions. • Besides pure CO 2 , diluted and impure CO 2 could successfully be used as feedstocks. • Recyclability and deactivation of the catalysts were studied. The development of fully heterogeneous catalysts for the widely investigated cycloaddition reaction of CO 2 to epoxides is crucial to achieve the sustainable synthesis of cyclic organic carbonates as useful emerging intermediates and building blocks. Nevertheless, relatively few fully heterogeneous catalytic systems exist for the title reaction with the ability to convert CO 2 to carbonates under atmospheric pressure and mild temperatures especially when using diluted and/or impure CO 2 as found in real case scenarios. Moreover, such catalysts are generally constituted by organic or metal–organic frameworks whose preparation generally involves the use or synthesis of expensive building blocks. In this work, we devised a convenient strategy to prepare single-component heterogeneous catalysts based on readily available metal halides and quaternary ammonium halide-based ionic liquids that started from a systematic evaluation of the corresponding homogeneous binary catalysts. This was followed by the preparation of silica-supported heterogeneous systems with different loadings of both catalytic components whose nature and composition were carefully studied through several characterization techniques (elemental analysis, FT-IR, ICP-OES, SEM and TEM microscopies, TGA analysis and XPS). The thus prepared catalysts showed the ability to carry out the cycloaddition of CO 2 to several epoxide under atmospheric pressure at mild temperatures (25–40 °C) including when using diluted CO 2 mixtures resembling low-calorific landfill gas with or without poisoning additives (H 2 S). Finally, the fate of the catalysts after reaction and their deactivation through the catalytic cycles is discussed.

Catalytic hydrothermal liquefaction of peanut shell for the production aromatic rich monomer compounds

Industrial wastes and natural mixed oxide materials were evaluated as inexpensive heterogeneous catalysts for catalytic hydrothermal liquefaction (HTL) of food wastes. Base MgO and ZSM-5 and mixture of MgO + ZSM-5 achieved bio-oil yields of 31.2, 35.5, and 40.6 wt% with higher heating values (HHVs) of 32.5–34.8 MJ kg-1, respectively, which were much greater than those without the catalyst. Bio-oil characterization revealed that similar families of molecules were formed in the presence and absence of catalysts, implying that the main role of the catalyst is to promote rates of thermal reactions, leading to Bio-oil production. The improved catalytic HTL performance of the mixed metal oxides compared with single-metal oxides was attributed to the synergistic effects of base and acid sites present on catalyst surfaces. Maximum yield of aromatic hydrocarbon compounds (49%) observed in case of HTL with MgO + ZSM-5 mixture catalyst. The percent of energy recovered as bio-oil was strongly correlated with the base-to-acid site density ratio, providing an important performance predictor for catalyst HTL conversion of food waste to bioenergy.

Activated charcoal supported copper nanoparticles: A readily available and inexpensive heterogeneous catalyst for the N-arylation of primary amides and lactams with aryl iodides

Abstract A novel heterogeneous copper catalyst has been developed by supporting copper nanoparticles on activated charcoal via in situ reducing copper(II) with aqueous hydrazine as reductant. The characterization of Cu/C catalyst showed that the Cu0 nano-particles were formed on the surface of charcoal. This catalyst displayed good catalytic activities toward the N-arylation of primary amides and lactams with aryl iodides.

Synergistic Effects of Inexpensive Mixed Metal Oxides for Catalytic Hydrothermal Liquefaction of Food Wastes

Industrial wastes and natural mixed oxide materials were evaluated as inexpensive heterogeneous catalysts for catalytic hydrothermal liquefaction (CHTL) of food wastes. Red mud and red clay achieve...

KF/clinoptilolite nanoparticles as an efficient nanocatalyst for the Strecker synthesis of α-aminonitriles

Potassium fluoride impregnated on clinoptilolite nanoparticles (KF/CP NPs) have been explored to serve as an effective and inexpensive heterogeneous catalyst for the one-pot three-component Strecker synthesis of a variety of α-aminonitriles at room temperature in ethanol as a green solvent. KF/CP NPs have been synthesized using simple impregnation techniques in aqueous media from readily available inexpensive starting materials and displayed its initial catalytic activity even after five runs. The easy preparation and separation of catalyst, simple procedure, mild reaction conditions, and excellent yields of products render this method as an attractive sustainable option.

Selective N‐Monomethylation of Anilines with Methanol Catalyzed by Commercial Pd/C as an Efficient and Reusable Catalyst

AbstractN‐methylation of amines is one of the most important C−N bond‐forming reactions and is widely utilized for the synthesis of numerous agrochemicals, drugs, natural products, and dyes. In this paper, the N‐monomethylation of aniline derivatives using Pd/C catalyst and methanol as the methylation reagent was investigated. The N‐monomethylation of various anilines was achieved with high activity and selectivity under relatively mild reaction conditions, and the yield of N‐monomethyl anilines was over 90 %. Notably, the commercial, readily available, and inexpensive heterogeneous catalyst, Pd/C, could be easily recovered and reused more than five times with only a slight decrease in activity; gram‐scale experiments were also successfully performed.

Anchoring of triethanolamine–Cu(II) complex on magnetic carbon nanotube as a promising recyclable catalyst for the synthesis of 5-substituted 1H-tetrazoles from aldehydes

The development of heterogenization of copper nanoparticles on conductive supports is very challenging and has received much attention. Here, we synthesize a practical, efficient, and inexpensive heterogeneous catalyst to grow stable metallic copper(II) nanoparticles on the surface of magnetic carbon nanotube (Fe3O4-CNT) catalyst support physically functionalized with triethanolamine (TEA) that acts as a low-cost and non-toxic ligand to capture the copper nanoparticles [Fe3O4-CNT-TEA-Cu(II)]. The as-prepared heterogeneous catalyst was characterized by different techniques, such as Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, vibrating sample magnetometer, X-ray diffraction patterns, field-emission scanning electron microscopy, and atomic absorption spectroscopy analysis. The catalytic behavior of Fe3O4-CNT-TEA-Cu(II) was investigated in the preparation of 5-substituted 1H-tetrazole derivatives via one-pot, three-component reaction between aromatic aldehydes, hydroxylamine, and sodium azide. The low catalyst loading, wide substrate scope, use of inexpensive materials, simple separation of the catalyst from the reaction mixture by an external magnet, short reaction times, easy workup, affordability, and superb yield are some advantages of this protocol.

A Highly Efficient and Recyclable Solid Acid Catalyst for Synthesis of Spiro-oxindole Dihydroquinazolinones Under Ultrasound Irradiation

A simple, efficient and green procedure for the synthesis of spiro-oxindole dihyfroquinazolinones was developed by multi-component condensation of isatoic anhydride, aniline and isatin in the presence of a novel solid acid catalyst under ultrasound irradiation. The present environmentally benign protocol offers several advantages, such as shorter reaction time, a wide range of functional group tolerance, the use of an inexpensive heterogeneous catalyst, and a high yield of products via a simple experimental and work-up procedure. The mesoporous solid acid catalyst was directly prepared from phytic acid by microwave-sulfonation method without template. The phytic acid based solid acid was fully characterized by means of Fourier transform infrared spectroscopy(FTIR), Raman spectroscopy, X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), and transmission electron microscopy(TEM). The catalyst can be recovered and reused for at least five runs without significant impact on the product yields.

Catalytic Conversion of CO2 to Cyclic Carbonates through Multifunctional Zinc‐Modified ZSM‐5 Zeolite

The production of fine chemicals using CO2 as C1 building block through inexpensive heterogeneous catalysts with high efficiency under low pressure is challenging. Herein we propose for the first time the utilization of a multifunctional heterogeneous zinc‐modified HZSM‐5 (ZnHZSM‐5) catalyst for upgrading CO2 by incorporation into cyclic carbonates from CO2 and epoxides. Owing to the nice surface properties such as abundant Lewis acid, Brønsted acid and Lewis base sites, large surface area, and plenty of micropores, CO2 could be concentrated and well activated in ZnHZSM‐5 verified by CO2‐TPD, TG‐MS, etc. Meanwhile, the epoxides were also activated through metal center and hydrogen bond. Therefore, the reaction can easily assemble at the catalyst interface and show exceptional performance, affording the aimed products with high yield of up to 99% in the presence of commercial tetra‐n‐propylammonium bromide (90% in kilogram scale with 0.004 mol% ZnHZSM‐5 and 0.015 mol% nPr4NBr).

A highly efficient and recyclable silica-supported tungstic acid (STA) catalyst for the synthesis of pyrano[3,2-c]chromen-5-ones under solvent free conditions

A simple, efficient, green and solvent-free procedure for the synthesis of pyrano[3,2-c]chromen-5-ones has been developed by multi-component condensation of 4-hydroxycoumarin, aldehydes and (E)-N-methyl-1-(methylthio)-2-nitroethenamine in the presence of a catalytic amount of silica-supported tungstic acid (STA). The reaction transformation presumably occurs via Knoevenagel condensation, Michael addition, imine-enamine tautomerism intramolecular, O-cyclization, elimination of MeSH. The present environmentally benign protocol offers several advantages such as shorter reaction times, a wide range of functional group tolerance, use of an inexpensive heterogeneous catalyst, and high yield of products via a simple experimental and work-up procedure. The catalyst can be recovered and reused for at least four runs without any significant impact on the product yields.

Cu–Ag/hydrotalcite catalysts for dehydrogenative cross-coupling of primary and secondary benzylic alcohols

The development of new and inexpensive heterogeneous catalysts for direct C–C cross-coupling of primary and secondary alcohols is a challenging goal and has great importance in academic and industrial sectors.

ChemInform Abstract: Solvent‐Free Condensation of 2‐Naphthol with Aromatic Aldehydes and Acetamide/Urea to 1‐Amidoalkyl‐2‐naphthols.

AbstractA new, clean and efficient solvent‐free method for the synthesis of 1‐amidoalkyl‐2‐naphthols via a one‐pot three‐component condensation reaction using silica‐supported phosphorus‐containing reagents Silphos or Silphox as inexpensive heterogeneous catalysts is developed.

Mannich reaction of secondary amines, aldehydes and alkynes in water using Cu/C nanoparticles as a heterogeneous catalyst

The use of 2 mol% of Cu/C nanoparticles, as an easily accessible and inexpensive heterogeneous catalyst, promoted a one-pot three-component condensation of an amine, aldehyde, and an alkyne in water to produce the corresponding propargylamine in good to high yields. This method was proved to be applicable to a wide range of substrates and is especially practical for the synthesis of new azacrown ether derivatives. The catalyst was quantitatively recovered from the reaction by a simple filtration and reused for at least ten times with almost consistent activity.

Preparation and characterization of inexpensive heterogeneous catalysts for air pollution control: Two case studies

Relatively inexpensive heterogeneous catalysts for two reactions of great importance in air pollution control, NO reduction and VOC combustion, were prepared and characterized. Apart from their common practical goal and the frequent need for simultaneous removal of air pollutants, these reactions share a similar redox mechanism, in which the formulation of more effective catalysts requires an enhancement of oxygen transfer.For NO reduction, supported catalysts were prepared by adding a metal (Cu, Co, K) using ion exchange (IE) and incipient wetness impregnation (IWI) to chars obtained from pyrolysis of a subbituminous coal. The effects of pyrolysis temperature, between 550 and 1000°C, on selected catalyst characteristics (e.g., BET surface area, XRD spectrum, support reactivity in O2) are reported. For IE catalysts, the surface area increased in the presence of the metals while the opposite occurred for IWI catalysts. For the Co-IE catalysts, the highest surface area was obtained at 700°C. The XRD results showed that, except for Cu (which exhibited sharp Cu0 peaks), the catalysts may be highly dispersed (or amorphous) on the carbon surface. For the C–O2 reaction the order of (re)activity was K≫Co>Cu for IE catalysts and K>Cu>Co for IWI catalysts. For NO reduction the orders were K>Co>Cu (IE catalysts) and Cu>Co>K (IWI catalysts). In all cases the catalytic (re)activity for NO reduction was lower than that exhibited for the C–O2 reaction. The K-IE and Cu-IWI catalysts appeared to be the most promising ones, although further improvements in catalytic activity will be desirable. Some surprising results regarding CO and CO2 selectivity are also reported, especially for Co catalysts.In VOC combustion, the effect of the nature of ion B (Fe and Ni) on the partial substitution of ion A (Ca for La) in ABO3 perovskites (e.g., LaFeO3 and LaNiO3) and on their catalytic activity was studied. The perovskite-type oxides were characterized by means of surface area measurements, XRD, temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR). The effect of partial substitution of La3+ by Ca2+ was more significant for the La1−xCaxFeO3 perovskites. In this case, the electronic perturbation is compensated by an oxidation state increase of part of Fe3+ to Fe4+. The TPD results revealed that, at higher substitution levels, oxygen vacancies are also formed to preserve electroneutrality. For the La1−xCaxNiO3 perovskites, the characterization results showed no evidence of large differences in electronic properties as calcium substitution increases. The La1−xCaxNiO3 perovskites exhibited lower activity than the simple LaNiO3 perovskite, whereas for the La1−xCaxFeO3 substituted perovskites the most active catalyst (exhibiting the lowest ignition temperature) was obtained at the highest substitution level, La0.6Ca0.4FeO3.The performance of both groups of catalysts is briefly discussed in terms of redox processes, in which the interplay between oxygen transfer and electron transfer requires further elucidation for the improvement of catalytic activity.

ChemInform Abstract: Nickel on Charcoal (“Ni/C”): An Expedient and Inexpensive Heterogeneous Catalyst for Cross‐Coupling Between Aryl Chlorides and Organometallics. Part 1. Functionalized Organozinc Reagents.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Nickel on Charcoal (“Ni/C”): An Expedient and Inexpensive Heterogeneous Catalyst for Cross-Couplings between Aryl Chlorides and Organometallics. I. Functionalized Organozinc Reagents

Nickel on Charcoal (“Ni/C”): An Expedient and Inexpensive Heterogeneous Catalyst for Cross-Couplings between Aryl Chlorides and Organometallics. I. Functionalized Organozinc Reagents