Heterogeneous Catalytic Synthesis Research Articles

A review of process of methanol carbonylation to produce acetic acid

Acidic corrosion plays a significant part in the compound business, particularly in the production of new substance fiber. As of now, the primary technique for creating acidic corrosive is the carbonylation of methanol utilizing iridium or rhodium organometallic edifices. The delegate techniques and the most recent advancement of methanol carbonylation to deliver acidic corrosion from two parts of homogeneous catalysis and heterogeneous catalysis are explored efficiently. The present homogeneous catalytic method and heterogeneous catalytic synthesis method using two different catalytic systems are introduced, followed in chronological order by the traditional method of producing acetic acid by carbonylation of methanol in the history of the chemical industry. The primary issues with producing acetic acid using conventional techniques are examined, including the product separation and the costly catalyst recovery. These issues can be resolved by developing and perfecting heterogeneous catalytic systems. The benefits and drawbacks of conventional techniques are broken down, the comprehensive summary and critical analysis of previous research provide comprehensive background knowledge, and the future exploration bearing is to work on the heterogeneous synergist framework to accomplish higher selectivity and preservation rate and work on financial proficiency.

Catalytic cycloaddition of CO2 to epoxidized methyl oleate over a HBimCl-NbCl5/HCMC: Physicochemical, mass transfer and kinetic investigation

The cycloaddition of CO2 to epoxidized molecules is an ecofriendly strategy for synthesizing aliphatic carbonates. In this study, heterogeneous catalytic synthesis of carbonated methyl oleate was performed. Influences of reaction parameters such as reaction temperature (403.15–443.15 K), pressure (1–3 MPa), concentration of functional groups (1.22–2.88 mol·L−1) and catalyst loading (0.025–0.042 g·mL−1) on the kinetics were evaluated. Gas-liquid mass transfer of CO2 in the methylated oleic acid system was investigated, and a mathematical model was developed. The dissolution of CO2 was found to be exothermic, and the dissolution capacity decreases with increasing temperature and decreasing pressure. The solubility of CO2 follows an order of methylated form > epoxidized form > carbonated form. A high conversion rate (68.45 %) of epoxides was achieved in 6 h at 443.15 K and 3 MPa with a catalyst loading of 0.042 g·mL−1. These results show a potential route for synthesizing aliphatic carbonates by combining methyl oleate with CO2.

Comprehensive study on selective dehydrochlorination of 2-chloro-3,3,3-trifluoropropene over carbon-based catalysts and catalyst deactivation

3,3,3-trifluoropropyne (HFY-2223tz) is a novel refrigerant with great physicochemical properties. Though preparation of HFY-2223tz from halogenated olefins is theoretically effective, it remains great challenges for dehydrohalogenation from halogenated olefins, limiting the detailed knowledge. Here, we established a facile investigation to explore the gas-phase dehydrochlorination reaction of 2‑chloro-3,3,3-trifluoropropene (HCFO-1233xf) over various halides (Na, K, Rb, Cs) supported active carbon (AC) catalysts. The CsF was concluded as the optimal active component with best dehydrochlorination selectivity and conversion of HCFO-1233xf. The CO2-TPD results illustrated that dehydrochlorination of HCFO-1233xf proceeded through E1cB mechanism. Mechanism study revealed the evolution of side-products including (Z/E)-1,3,3,3-tetrafluoropropylene, 2,3,3,3-tetrafluoropropylene, (Z/E)-1‑chloro‑3,3,3-trifluoroproene, and 3,3,3-trifluoroprop-1-ene, etc. However, observable deactivation of CsF catalyst was noticed, which, according to combined XRD and XPS results and density functional theory (DFT) calculations, was attributed to the F/Cl exchange between HCFO-1233xf and catalyst, leading to rapid fluorine consumption. This work thus provides basic knowledge about heterogeneous catalytic synthesis of HFY-2223tz from dehydrohalogenation of halogenated olefins.

Recent Advances in the Efficient Synthesis of Useful Amines from Biomass-Based Furan Compounds and Their Derivatives over Heterogeneous Catalysts

Bio-based furanic oxygenates represent a well-known class of lignocellulosic biomass-derived platform molecules. In the presence of H2 and different nitrogen sources, these versatile building blocks can be transformed into valuable amine compounds via reductive amination or hydrogen-borrowing amination mechanisms, yet they still face many challenges due to the co-existence of many side-reactions, such as direct hydrogenation, polymerization and cyclization. Hence, catalysts with specific structures and functions are required to achieve satisfactory yields of target amines. In recent years, heterogeneous catalytic synthesis of amines from bio-based furanic oxygenates has received extensive attention. In this review, we summarize and discuss the recent significant progress in the generation of useful amines from bio-based furanic oxygenates with H2 and different nitrogen sources over heterogeneous catalysts, according to various raw materials and reaction pathways. The key factors affecting catalytic performances, such as active metals, supports, promoters, reaction solvents and conditions, as well as the possible reaction routes and catalytic reaction mechanisms are studied and discussed in depth. Special attention is paid to the structure–activity relationship, which would be helpful for the development of more efficient and stable heterogeneous catalysts. Moreover, the future research direction and development trend of the efficient synthesis for bio-based amines are prospected.

Linear diketones as next-generation biomass-derived platform molecules: from heterogeneous catalytic synthesis to supply of high-end chemicals

This review presents the heterogeneous synthesis system and valorization routes of biomass-derived linear diketones as next-generation platform molecules.

Ionic porous organic polymer (IPOP) based on twisted biphenyl Scaffold: Green and efficient heterogeneous catalytic synthesis of β-Arylthioketones and biscoumarins

A new viologen-based ionic porous organic polymer (IPOP) has been developed based on a twisted biaryl (TMBB) as the monomer and Menshutkin reaction as the polymerization reaction. IPOP is thermally stable and insoluble in H2O and common organic solvents (MeOH, MeCN, EtOH, DCM, etc.). The presence of cationic sites as well as counter bromide anions in the polymeric matrix endow the IPOP with properties akin to those of the phase-transfer quaternary ammonium salt, namely TBAB, to permit its application as a recyclable heterogeneous catalyst for organic transformations. It’s shown that IPOP can be readily applied as a phase-transfer catalyst for Michael addition of thiols to α,β-unsaturated carbonyl compounds, providing access to organosulfur compounds, namely, β-arylthioketones, in excellent isolated yields. In a similar manner, IPOP is shown to be applicable as a recyclable heterogeneous catalyst for facile synthesis of biscoumarins, which are an important class of molecular systems exhibiting a variety of biological activities such as anti-coagulant, anti-anthelmintic, anti-HIV, anti-bacterial, anti-oxidant, anti-cancer, etc. Thus, a novel, efficient and ecofriendly approach in a manner mimicking the phase-transfer quaternary ammonium salts has been developed for the synthesis of β-arylthioketones and biscoumarins; the IPOP can be employed as a heterogeneous catalyst for at least 10 catalytic cycles without any loss of catalytic activity.

Molybdenum carbide phase effects in heterogeneous catalytic ammonia synthesis

The design of an efficient catalyst utilizing non-precious metals is a top priority in ammonia synthesis, and Mo is found to be inferior in ammonia synthesis due to strong nitrogen adsorption. The carburization of Mo species might be an ideal strategy for optimizing nitrogen adsorption energy and ammonia synthesis activity. In this work, we prepare two molybdenum carbides with different crystal structures (α-MoC and β-Mo2C). The result shows that there is a larger number of Mo-C bonds and lower Mo/C ratio in α-MoC, leading to the strong adsorption of hydrogen and ammonia species on α-MoC. In contrast, the desorption energies of hydrogen and ammonia are lower for β-Mo2C, and the spillover and migration of hydrogen species are boosted. The facile desorption of hydrogen and ammonia species also limits the accumulation of H adatoms and ammonia on the surface of β-Mo2C, releasing of active sites available for the subsequent activation of hydrogen and nitrogen as well as ammonia synthesis reaction. As a result, the ammonia synthesis activity of β-Mo2C catalyst is 2.5-fold higher than that of α-MoC, and a small negative value of NH3 reaction order also would be obtained for β-Mo2C. This work not only reports the effect of molybdenum carbide phases on the adsorption–desorption properties of reactants and catalytic activities for ammonia synthesis, but also opens a perspective for the design and development of efficient metal based heterogeneous catalysts by tuning the adsorption and desorption properties of the reactant gases. Keywords: Molybdenum Carbide; Phase effect; Adsorption–desorption property; Mo catalyst; Ammonia synthesis

Reductive C-N Coupling of Nitroarenes: Heterogenization of MoO3 Catalyst by Confinement in Silica.

The construction of C-N bonds with nitroaromatics and boronic acids using highly efficient and recyclable catalysts remains a challenge. In this study, nanoporous MoO3 confined in silica serves as an efficient heterogeneous catalyst for C-N cross-coupling of nitroaromatics with aryl or alkyl boronic acids to deliver N-arylamines and with desirable multiple reusability. Experimental results suggest that silica not only heterogenizes the Mo species in the confined mesoporous microenvironment but also significantly reduces the reaction induction period and regulates the chemical efficiency of the targeted product. The well-shaped MoO3 @m-SiO2 catalyst exhibits improved catalytic performance both in yield and turnover number, in contrast with homogeneous Mo catalysts, commercial Pd/C, or MoO3 nanoparticles. This approach offers a new avenue for the heterogeneous catalytic synthesis of valuable bioactive molecules.

Lignin amination valorization: heterogeneous catalytic synthesis of aniline and benzylamine from lignin-derived chemicals

Using lignin derivatives as substrates, important organic nitrogen chemicals such as aniline and benzylamine can be obtained with high selectivity through heterogeneous catalyzed amination.

Correction: Lignin amination valorization: heterogeneous catalytic synthesis of aniline and benzylamine from lignin-derived chemicals

Correction for ‘Lignin amination valorization: heterogeneous catalytic synthesis of aniline and benzylamine from lignin-derived chemicals’ by Yue Rong et al., Green Chem., 2021, DOI: 10.1039/d1gc02741g.

Heterogeneous Catalytic Synthesis of Zingerone and Dehydrozingerone

Results of a single-stage heterogeneous catalytic synthesis of zingerone and dehydrozingerone have been described. The prospects of the proposed approach have been shown; the main kinetic laws governing the reaction have been revealed. Optimum conditions for zingerone and dehydrozingerone synthesis providing a yield of the target products of 45.8 and 76.2%, respectively, have been found.

Heterogeneous Catalytic Synthesis of Methyl Lactate and Lactic Acid from Sugars and Their Derivatives.

Recent developments in sugar transformations to methyl lactate and lactic acid are critically summarized. The highest yield of methyl lactate from glucose obtained over Sn(salen)/octylmethyl imidazolium bromide catalyst was 68 % at 160 °C whereas the highest yield of lactic acid of 58 % was achieved over hierarchical Lewis acidic Sn‐Beta catalysts at 200 °C under inert atmosphere. In addition to the desired products also humins are formed in water whereas in methanol alkyl glucosides‐ and ‐fructosides as well as acetals were generated, especially in the presence of Brønsted‐acidic sites. The main challenges limiting the industrial feasibility of these reactions are incomplete liquid phase mass balance closure, complicated product analysis and a lack of kinetic data. In addition to reporting optimized reaction conditions and catalyst properties also catalyst reuse and regeneration as well as kinetic modelling and continuous operation are summarized.

In-situ grafting of N-doped carbon nanotubes with Ni encapsulation onto MOF-derived hierarchical hybrids for efficient electrocatalytic hydrogen evolution

Developing highly efficient and cost-effective catalysts for the hydrogen evolution reaction (HER) is of paramount importance to solve the problems arising from the depletion of non-renewable fossil fuels and increasing air pollution issues. Herein, an in-situ heterogeneous catalytic synthesis approach is developed for constructing hierarchical Ni/carbon hybrids via grafting nitrogen-doped-carbon (NC) nanotubes with Ni encapsulation onto the metal-organic framework (MOF)-derived carbon matrix. Following the “nanotube tip-growth model” involved in the in-situ catalytic synthesis process, the morphology and size of the nanotubes and encapsulated particles of the as-prepared hierarchical Ni-based carbon hybrids can be controlled by regulating the conditions during the thermal decomposition of the Ni-MOF in the presence of melamine. The grafting and decoration of the Ni-encapsulated carbon nanotubes on the MOF-derived architecture rapidly enhance the HER electrocatalytic performance of the bare thermally decomposed Ni/N-doped carbon composite. Due to the synergistic effects of the stable metallic Ni active sites and the N-doped carbon support, the optimized Ni@NC6-600 sample exhibits stable and high catalytic activity, only requiring an overpotential of 181 mV to drive 10 mA/cm2 towards the HER in alkaline media.

Ion-imprinted mesoporous silica/magnetic graphene oxide composites functionalized with Schiff-base for selective Cu(II) capture and simultaneously being transformed as a robust heterogeneous catalyst

Ascribing to the risk on public health and environment, as well as the extensive applications of copper, the highly selective capture and effective utilization of the recovered Cu(II) ion by using a multifunctional material are of significant practical interest. However, there remains an arduous challenge to the fulfillment of such tasks. In this study, using the mesoporous silica/magnetic graphene oxide composites (MS/MGO) as the support, 2-((2-(3-(trimethoxysilyl)propylamino)ethylimino)methyl)phenol (TPEMP) bearing Schiff-base as the functional monomer, surface Cu(II) ion-imprinted polymers (Cu(II)-IIPs) were fabricated and applied for the selective capture Cu(II) ion from aqueous media. Additionally, the reuse of the spent Cu(II) loaded adsorbent (SMS/MGO-Cu) to the catalytic application was also explored. The obtained samples were characterized by various techniques. The uptake of Cu(II) by Cu(II)-IIP-2 was tested through the study of pH effect, sorption isotherms and uptake kinetics, selective sorption, adsorbent regeneration. The results indicated the Cu(II)-IIP-2 had high selectivity and faster kinetic over reported adsorbents, with an equilibrium adsorption capacity of 195.3 mg/g at 298 k within 30 min. Sorption isotherms were well described by the Langmuir model, while the uptake kinetics was fitted by the pseudo-second order rate equation. In addition, the Cu(II)-IIP-2 could be recycled six times without any significant loss in adsorption capacity. Importantly, the best catalysis efficiency of SMS/MGO-Cu for the synthesis of 1-methyl-4-(p-tolyloxy)benzene was 95%. These results indicate the Cu(II)-IIP-2 can not only be applied to effectively remove Cu(II) ion from aqueous media, but also be used in heterogeneous catalytic organic synthesis reactions after sorption.

Industrial disposal processes for treatment of polychlorinated dibenzo-p-dioxins and dibenzofurans in municipal solid waste incineration fly ash.

Hazardous waste disposal is a serious environmental concern in China. Therefore, in this study, industrial trials were conducted in a low-temperature thermal degradation facility, a tunnel kiln, and a shaft kiln to effectively treat dioxins in municipal solid waste incineration (MSWI) fly ash. The results indicated that the low-temperature thermal degradation facility efficiently decomposed polychlorinated dibenzo-p-dioxins and dibenzofurans in the MSWI fly ash. Additionally, the concentrations of dioxins in the treated fly ash and exhaust gas were lower than the suggested standard limits and the degradation ratio of dioxins was ∼99%. Therefore, treated fly ash characterized by acceptable dioxin risks could be utilized for the production of non-fired building materials. The results from the tunnel kiln indicated complete decomposition of the dioxins in the firing and insulating sections. However, the addition of fly ash in the tunnel kiln increased the concentration of dioxins in the flue gas. This can be primarily attributed to the heterogeneous catalytic synthesis reaction in the low-temperature section of the tunnel kiln. The results from the shaft kiln indicated degradation of at least 22% of the dioxins in the ash. The dioxin concentration in the flue gas was lower than the national standard while that in the clinker was within a reasonable limit. Furthermore, the environmental risks were significantly reduced at fly ash addition ratios lower than 3%.

Organic Synthesis Using Environmentally Benign Acid Catalysis.

Recent advances in the application of environmentally benign acid catalysts in organic synthesis are reviewed. The work includes three main parts; (i) description of environmentally benign acid catalysts, (ii) synthesis with heterogeneous and (iii) homogeneous catalysts. The first part provides a brief overview of acid catalysts, both solid acids (metal oxides, zeolites, clays, ion-exchange resins, metal-organic framework based catalysts) and those that are soluble in green solvents (water, alcohols) and at the same time could be regenerated after reactions (metal triflates, heteropoly acids, acidic organocatalysts etc.). The synthesis sections review a broad array of the most common and practical reactions such as Friedel-Crafts and related reactions (acylation, alkylations, hydroxyalkylations, halogenations, nitrations etc.), multicomponent reactions, rearrange-ments and ring transformations (cyclizations, ring opening). Both the heterogeneous and homogeneous catalytic synthesis parts include an overview of asymmetric acid catalysis with chiral Lewis and Brønsted acids. Although a broad array of catalytic processes are discussed, emphasis is placed on applications with commercially available catalysts as well as those of sustainable nature; thus individual examples are critically reviewed regarding their contribution to sustainable synthesis.

Electrochemical Synthesis of Ammonia Using Origami-like Molybdenum Carbide Nanoflakes As Nitrogen Reduction Reaction Catalyst

Ammonia plays a crucial role in feeding the majority of today’s population and its production has increased from a few thousand tons per year in 1908 to above 100 million tons per year today, revolutionizing the fertilizer industry thanks to the Haber-Bosch (HB) process. However, the HB process is highly energy intensive consuming about 1.4 % of the fossil energy generated worldwide and releasing 1.87 tons of the greenhouse gas CO2 into the environment per ton of ammonia synthesized. Hence, finding alternative and energy efficient ways to synthesize ammonia under milder conditions is important from more than one perspective. The challenge associated with NH3 synthesis from its constituent nitrogen and hydrogen gases is breaking the strong N≡N bond (947 kJmol-1). While heterogeneous catalytic synthesis needs high temperature and pressure operation, electrochemical synthesis routes offer a milder approach. However, electrochemical synthesis of ammonia under different temperatures, utilizing different electrolytes and catalysts has not yet reliably produced ammonia at viable rates and efficiencies. We report a Mo2C cathode catalyst for ammonia synthesis that has demonstrated synthesis rates on the order of 2x10-12 molcm-2s-1 for more than 24 hours at 30 °C using Nafion 212 as the electrolyte and Pt/C as the anode. The β-Mo2C has a hexagonal lattice structure with an origami-like morphology containing numerous kinks which may improve its electrocatalytic activity. The maximum synthesis rate was obtained at -0.5 V, however, the faradaic efficiency decreased with increasing over-potential. This catalyst offers a promising alternative for producing ammonia especially with electrolytes that conduct protons under dry conditions. This presentation further covers the utility of Nafion as an electrolyte for electrochemical ammonia synthesis.

Heterogeneous Catalytic Synthesis of 2-Methylbenzimidazole from 2-Nitroaniline and Ethanol Over Mg Modified Cu-Pd/γ-Al2O3

The direct synthesis of benzimidazoles from 2-nitroaniline and ethanol over Cu-Pd/γ-Al2O3 catalysts has the advantages of requiring easily available starting materials, having high efficiency, and a simple procedure. The modification by Mg of the Cu-Pd/γ-Al2O3 catalyst could improve the catalytic activity significantly. The addition of Mg to the Cu-Pd/γ-Al2O3 catalyst could maintain and promote the formation of CuPd alloy active sites. Meanwhile, the basicity of the support was enhanced appropriately by Mg, which generated more basic sites (Al-Oδ−) to accelerate the dehydrogenation of alcohol and increased the rate of the whole coupled reaction. The 2-nitroaniline was completely converted over Cu-Pd/(Mg)γ-Al2O3 after reacting for six hours, and the yield of 2-methylbenzimidazole was 98.8%. The results of this work provide a simple method to develop a more efficient catalyst for the “alcohol-dehydrogenation, hydrogen transfer and hydrogenation” coupled reaction system.

Synthesis of cinnamyl benzoate over novel heteropoly acid encapsulated ZIF-8

ZIF-8 is a zeolitic imidazolate framework which is a subclass of metal organic framework (MOF). ZIF-8 is the emerging class of MOF with various applications. Dodecatungstophosphoric acid (DTP) encapsulated ZIF-8 was prepared first time using bottle around the ship strategy. This approach covers ZIF-8 synthesis along with DTP encapsulation in one pot synthesis. The synthesized catalyst shows highest catalytic activity for esterification reaction of benzoic anhydride with cinnamyl alcohol to form cinnamyl benzoate. Heterogeneous catalytic synthesis of cinnamyl benzoate with complete reaction kinetics is presented here for the first time. Cinnamyl benzoate is a famous perfumery and flavoring agent and GRAS listed food additive molecule. Catalyst preparation method is simple, rapid and can be done at room temperature using water as a solvent. DTP@ZIF-8 shows sodalite like structure and it was confirmed by applying several characterization techniques like SEM, TEM, XRD, BET, FTIR, TGA and ammonia-TPD. Duration of DTP@ZIF-8 crystal formation was studied and optimized up to 12 h. Catalyst is thermally stable up to 400 °C and showed reusability for 3 cycles. Reaction kinetics was studied with best fit of Eley-Rideal mechanism.

Heterogeneous Catalytic Synthesis of Organic Compounds Labeled with Hydrogen Isotopes without Using Solvents

Solid-phase procedures for hydrogenolysis, hydrogenation, and isotope exchange are described. The possibilities of the solid-phase method for deuterium or tritium labeling of organic compounds are demonstrated. The influence of the reaction conditions on the yield of the labeled products and on the degree of hydrogen isotope incorporation into them is considered. An attempt is made to rationalize the data obtained by processes occurring in the hydrogen isotope–catalyst–support–substrate system.