Dimethoxymethane as a Cleaner Synthetic Fuel: Synthetic Methods, Catalysts, and Reaction Mechanism

Using Support Effects to Increase the Productivity of Immobilized Ruthenium Hydride Catalysts for the Hydrogenation of CO2

Interfaces between catalytically active metal surfaces/sites and metal oxides (such as those formed by metal oxides covering metal nanoparticles by strong metal-support interactions) allow both the metal and metal oxide to react with substrates simultaneously and are important for the activity of many heterogeneously catalyzed reactions. However, similar interactions for well-defined immobilized catalysts have not been investigated, despite their potential for increasing catalytic activity. We test the reactivity of a ruthenium hydride [H2Ru(PPh3)2(Ph2P)2NC3H6Si(OEt)3 (1)] in the amine-promoted hydrogenation of CO2 as both a homogeneous catalyst and anchored on SiO2, Al2O3, ZnO, and SBA-15. Anchoring 1 on the surfaces resulted in varying degrees of surface collapse (formation of H-Ru-O linkages to the surface), with ZnO and confinement in SBA-15 pores giving the least surface collapse. Immobilization of 1 on ZnO gave a 6-fold improvement of the catalytic rate over the corresponding homogeneous catalyst. This increase in the catalytic productivity was only possible when the complex was in close contact with ZnO and is most likely due to a combination of increased catalytic activity and slower deactivation. These results demonstrate the ability of surface effects to vastly improve the productivity of even mediocre catalysts upon surface immobilization.

Selective reductive conversion of CO2 to CH2-bridged compounds by using a Fe-functionalized graphene oxide-based catalyst

Anthropogenic climate change drastically affects our planet, with CO2 being the most critical gaseous driver. Despite the existing carbon dioxide capture and transformation, there is much need for innovative carbon dioxide hydrogenation catalysts with excellent selectivity. Here, we present a fast, effective, and sustainable route for coupling diverse alcohols, amines and amides with CO2 via heterogenization of a natural metal-based homogeneous catalyst through decorating on functionalized graphene oxide (GO). Combined synthetic, experimental, and theoretical studies unravel mechanistic routes to convergent 4‑electron reduction of CO2 under mild conditions. We successfully replace the toxic and expensive ruthenium species with inexpensive, ubiquitously available and recyclable iron. This iron-based functionalized graphene oxide (denoted as Fe@GO-EDA, where EDA represents ethylenediamine) functions as an efficient catalyst for the selective conversion of CO2 into a formaldehyde oxidation level, thus opening the door for interesting molecular structures using CO2 as a C1 source. Overall, this work describes an intriguing heterogeneous platform for the selective synthesis of valuable methylene-bridged compounds via 4‑electron reduction of CO2.

Coupling photocatalytic CO2 reduction and CH3OH oxidation for selective dimethoxymethane production

Currently, conventional dimethoxymethane synthesis methods are environmentally unfriendly. Here, we report a photo-redox catalysis system to generate dimethoxymethane using a silver and tungsten co-modified blue titanium dioxide catalyst (Ag.W-BTO) by coupling CO2 reduction and CH3OH oxidation under mild conditions. The Ag.W-BTO structure and its electron and hole transfer are comprehensively investigated by combining advanced characterizations and theoretical studies. Strikingly, Ag.W-BTO achieve a record photocatalytic activity of 5702.49 µmol g-1 with 92.08% dimethoxymethane selectivity in 9 h of ultraviolet-visible irradiation without sacrificial agents. Systematic isotope labeling experiments, in-situ diffuse reflectance infrared Fourier-transform analysis, and theoretical calculations reveal that the Ag and W species respectively catalyze CO2 conversion to *CH2O and CH3OH oxidation to *CH3O. Subsequently, an asymmetric carbon-oxygen coupling process between these two crucial intermediates produces dimethoxymethane. This work presents a CO2 photocatalytic reduction system for multi-carbon production to meet the objectives of sustainable economic development and carbon neutrality.

Liquid foaming of TPU with Methylal

This work investigates the peculiarities of using a liquid blowing agent, namely dimethoxymethane (Methylal) to foam a thermoplastic polyurethane (TPU) in the laboratory practice of batch foaming equipment. We preliminarily measured thermodynamic properties of the polymer/gas system relevant to foaming, namely the vapor-liquid pressures at the TPU foaming temperatures. Three different paths were then explored for foaming. First, we used Methylal under its liquid-vapor equilibrium condition, in which both liquid and vapor are present. Secondly, we used Methylal in the liquid state to experiment with liquid foaming strategies. We have observed specific aspects, details, and issues related to the use of liquid blowing agents and devised strategies to deal with them. Finally, we used Methylal as a co-blowing agent together with CO2. In all cases, we examined the impact of pressure, pressure drop rate, and temperature on foam density and morphology. Overall, liquid foaming has proven to be a viable technique and Methylal an effective blowing agent, especially in cooperation with other gaseous blowing agents, where it significantly improves the expansion ratio of the final product.

Exploring the Water Oxidation Catalytic Activity of a Mn-Based Magnetic Metal-Organic Framework: The Role of Proton Conductivity and Oxygen Evolution Reaction Overpotential

The present work evaluates the water oxidation catalytic activity of a Mn-based metal-organic framework (MOF), which we envisioned to reduce the oxygen evolution reaction (OER) overpotential because of its high electrical conductivity, facilitated by solvent-encapsulated structural features. The presence of Mn centers induces interesting magnetic features in the MOF, which exhibits impressive cryogenic magnetic refrigeration with a ΔSM value of 29.94 J kg-1 K-1 for a field change of ΔH = 5T at 2.3 K. To the best of our knowledge, the ΔSM value of the current system ranked the highest position among the published examples. The crystal structure aligns perfectly with the thematic expectations and features as many as ten metal-coordinated water molecules, forming an extensive web of a hydrogen-bonded network while facing toward the porous channel filled with another set of much-anticipated entrapped lattice water molecules. Such structural features are expected to manifest high proton conductivity, and detailed investigation indeed yields the best value for the system at 1.57 × 10-4 S/cm at 95% humidity and 85 °C. In order to evaluate the thematic notion of a one-to-one relationship between OER and improved electrical conductivity, extensive electrocatalytic water splitting (WS) investigations were carried out. The final results show highly encouraging WS ability of the Mn-MOF, showing the electrocatalytic surface area value of the active species as 0.0686 F/g with a turnover frequency value of 0.043 [(mol. O2) (mol. Mn-MOF)-1 s-1]. Another fascinating aspect of the current communication is the excellent synergy observed between the experimental WS outcomes and the corresponding theoretical data calculated using density functional theory (DFT). Consequently, a plausible mechanism of the overall OER and the role of the Mn-MOF as a water oxidation catalyst, along with the importance of water molecules, have also been derived from the theoretical calculations using DFT.

Paired Electrosynthesis of Formaldehyde Derivatives from CO2 Reduction and Methanol Oxidation

Utilizing CO2 -derived formaldehyde derivatives for fuel additive or polymer synthesis is a promising approach to reduce net carbon dioxide emissions. Existing methodologies involve converting CO2 to methanol by thermal hydrogenation, followed by electrochemical or thermochemical oxidation to produce formaldehyde. Adding to the conventional methanol oxidation pathway, we propose a new electrochemical approach to simultaneously generate formaldehyde derivatives at both electrodes by partial methanol oxidation and the direct reduction of CO2 . To achieve this, a method to directly reduce CO2 to formaldehyde at the cathode is required. Still, it has been scarcely reported previously due to the acidity of the formic acid intermediate and the facile over-reduction of formaldehyde to methanol. By enabling the activation and subsequent stabilization of formic acid and formaldehyde respectively in methanol solvent, we were able to implement a strategy where formaldehyde derivatives were generated at the cathode alongside the anode. Further mechanism studies revealed that protons supplied from the anodic reaction contribute to the activation of formic acid and the stabilization of the formaldehyde product. Additionally, it was found that the cathodic formaldehyde derivative Faradaic efficiency can be further increased through prolonged electrolysis time up to 50 % along with a maximum anodic formaldehyde derivative Faradaic efficiency of 90 %.

Synthetic fuels: what are they and where do they come from?

Synthetic fuels are increasingly discussed when considering solutions to climate change mitigation. However, it is rather unclear what synthetic fuels are and their scope in replacing regular fossil fuels. Here, we propose a definition for synthetic fuels and discuss their classification based on production methods. These technologies are considered based on their scalability and extent of sustainability, along with the advantages they provide for overcoming renewable energy challenges.

Combustion, Chemistry, and Carbon Neutrality

Combustion is a reactive oxidation process that releases energy bound in chemical compounds used as fuels─energy that is needed for power generation, transportation, heating, and industrial purposes. Because of greenhouse gas and local pollutant emissions associated with fossil fuels, combustion science and applications are challenged to abandon conventional pathways and to adapt toward the demand of future carbon neutrality. For the design of efficient, low-emission processes, understanding the details of the relevant chemical transformations is essential. Comprehensive knowledge gained from decades of fossil-fuel combustion research includes general principles for establishing and validating reaction mechanisms and process models, relying on both theory and experiments with a suite of analytic monitoring and sensing techniques. Such knowledge can be advantageously applied and extended to configure, analyze, and control new systems using different, nonfossil, potentially zero-carbon fuels. Understanding the impact of combustion and its links with chemistry needs some background. The introduction therefore combines information on exemplary cultural and technological achievements using combustion and on nature and effects of combustion emissions. Subsequently, the methodology of combustion chemistry research is described. A major part is devoted to fuels, followed by a discussion of selected combustion applications, illustrating the chemical information needed for the future.

Stability and Reactivity of a Polyoxymethylene Dimethyl Ether over Typical Catalysts for Diesel Emission Control

Polyoxymethylene dimethyl ethers (OME) produced from methanol are considered as potential substitutes of Diesel fuel. Emissions of formaldehyde and other components have been observed, particularly under cold-start conditions in engine test-bench experiments with OME fuel. In this study, the reactivity of OME3 (CH3O(CH2O)3CH3) and its decomposition products was studied in the temperature range 80–450 °C in a model gas test bench over V2O5/WO3/TiO2 and Cu-CHA SCR catalysts, a platinum-coated V2O5/WO3/TiO2 ammonia slip catalyst (ASC) and two diesel oxidation catalysts (DOC), based on platinum and platinum-palladium. Already at 80 °C, OME3 was largely hydrolyzed to methanol and formaldehyde over all catalysts. At temperatures above 150 °C, V2O5/WO3/TiO2 oxidized methanol and formaldehyde to CO via formic acid as intermediate. The platinum ASC showed a similar behavior but oxidized the decomposition products to CO2. Whereas Cu-CHA hydrolyzed OME3 quantitatively to methanol and formaldehyde, it did not show oxidation activity in the studied temperature range. The data indicate that the release of significant amounts of OME from a catalytic converter can be virtually ruled out under cold start conditions, but also that low temperature hydrolysis produces formaldehyde and methanol emissions.

The Promoting Effect of Ti on the Catalytic Performance of V-Ti-HMS Catalysts in the Selective Oxidation of Methanol

The effects of Ti modification on the structural properties and catalytic performance of vanadia on hexagonal mesoporous silica (V-HMS) catalysts are studied for selective methanol-to-dimethoxymethane oxidation. Characterizations including N2 adsorption–desorption (SBET), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS UV-Vis), Micro-Raman spectroscopy, FTIR spectroscopy, and H2 temperature-programmed reduction (H2-TPR) were carried out to investigate the property and structure of the catalysts. The results show that Ti can be successfully incorporated into the HMS framework in a wide range of Si/Ti ratios from 50 to 10. Ti modification can effectively improve the distribution of vanadium species and thus enhance the overall redox properties and catalytic performance of the catalysts. The catalytic activity of the V-Ti-HMS catalysts with the Si/Ti ratio of 30 is approximately two times higher than that of V-HMS catalysts with comparable selectivity. The enhanced activity exhibited by the V-Ti-HMS catalyst is attributed to the improved dispersion and reducibility of vanadium oxides.

Selective oxidation conversion of methanol/dimethyl ether

As important platform compounds, methanol and dimethyl ether (DME) are vital bridges between the coal chemical, petrochemical and fine chemical industries. At present, the synthesis of methanol/DME has been industrialized, and the production capacity is much larger than the market demand. Therefore, the conversion of methanol/DME into more valuable chemicals is an important and significant topic. The synthesis of high value-added oxygenated chemicals and diesel oil additives from methanol/DME by an oxidation method has attracted substantial attention due to it being green and environmentally friendly and having good atom economy. In this feature article, we have summarized the recent advances in the synthesis of formaldehyde, methyl formate, dimethoxymethane, and polyoxymethylene dimethyl ethers, from the selective oxidation of methanol/DME, and further discussed the adsorption and activation of reactant molecules, selective cleavage of C-O, C-H or O-H bonds in methanol/DME molecules and the C-O chain growth in the target products. In the end, major challenges and future prospects are proposed from the viewpoint of catalyst design and application. It is expected that this feature article will provide theoretical guidance for the activation and cleavage of C-O, C-H, or O-H bonds in other small molecules of alcohol/ether as well as low-carbon alkanes, so as to synthesize high value-added chemicals.

Combination of Theoretical and Experimental Insights into the Oxygenated Fuel Poly(oxymethylene) Dibutyl Ether from n-Butanol and Paraformaldehyde

Oxygenated fuel has the function of self-supplying oxygen during the combustion process, which can greatly improve emission performance and reduce diesel fuel soot production. In this paper, a novel oxygenated fuel poly(oxymethylene) dibutyl ether (PODBE _n ) is designed and synthesized through experiments in combination with density functional theory (DFT) calculation. The experimental results show that PODBE _n has the advantages of high cetane number (73.6), moderate density (868 kg/m³), and low condensation point (-72 °C). According to the DFT calculation results, the molecular (PODBE _n ) polarity index of different polymerization degrees is similar to the value of diesel and has good mutual solubility with diesel. Moreover, the mechanism of the entire path of synthesis is calculated at the M06-2X/6-311G(d,p) level of theory. The energetic profile reveals that the rate-determining step is the nucleophilic addition step with the highest barrier energy (TS1 = 21.59 kcal/mol). This work provides a feasible method to synthesize high-performance oxygenated fuel PODBE _n using NKC-9 ion-exchange resins.

The unimolecular decomposition of dimethoxymethane: channel switching as a function of temperature and pressure

Branching ratios of competing unimolecular reactions often exhibit a complicated temperature and pressure dependence that makes modeling of complex reaction systems in the gas phase difficult. In particular, the competition...

Biomass-Based Carbon-Supported Sulfate Catalyst for Efficient Synthesis of Dimethoxymethane from Direct Oxidation of Dimethyl Ether

The synthesis of dimethoxymethane (DMM) from direct oxidation of dimethyl ether (DME) is a green and competitive route with good atomic economy and low carbon emission and is also an urgent need. In this work, biomass-based carbon-supported sulfate catalysts were designed and prepared for the efficient synthesis of DMM from DME oxidation. The prepared carbon support from cellulose displayed much larger specific surface area and a developed microporous structure, which effectively benefited a high dispersion of sulfate components, leading to mainly weak acid sites and more oxygen functional groups on the catalyst surface. The Ti(SO₄)₂/PC-H₂SO₄ catalyst exhibits excellent performance for DME oxidation with DMM_1-2 selectivity up to 96.7%, and DMM selectivity reaches 89.1%, notably higher than that of previously reported results. The distinctive surface structure and chemical properties of the carbon support have important impacts on the dispersion state of sulfate species, affecting the acidic and redox properties of the catalysts.

Near-Surface Gas-Phase Methoxymethanol Is Generated by Methanol Oxidation over Pd-Based Catalysts

Catalytic conversion of alcohols underlies many commodity and fine chemical syntheses, but a complete mechanistic understanding is lacking. We examined catalytic oxidative conversion of methanol near atmospheric pressure using operando small-aperture molecular beam time-of-flight mass spectrometry, interrogating the gas phase 500 μm above Pd-based catalyst surfaces. In addition to a variety of stable C_1-3 species, we detected methoxymethanol (CH₃OCH₂OH)─a rarely observed and reactive C₂ oxygenate that has been proposed to be a critical intermediate in methyl formate production. Methoxymethanol is observed above Pd, Au_xPd_y alloys, and oxide-supported Pd (common methanol oxidation catalysts). Experiments establish temperature and reactant feed ratio dependences of methoxymethanol generation, and calculations using density functional theory are used to examine the energetics of its likely formation pathway. These results suggest that future development of catalysts and microkinetic models for methanol oxidation should be augmented and constrained to accommodate the formation, desorption, adsorption, and surface reactions involving methoxymethanol.

Catalytic Reductive Alcohol Etherifications with Carbonyl-Based Compounds or CO2 and Related Transformations for the Synthesis of Ether Derivatives

Ether derivatives have myriad applications in several areas of chemical industry and academia. Hence, the development of more effective and sustainable protocols for their production is highly desired. Among the different methodologies reported for ether synthesis, catalytic reductive alcohol etherifications with carbonyl-based moieties (aldehydes/ketones and carboxylic acid derivatives) have emerged in the last years as a potential tool. These processes constitute appealing routes for the selective production of both symmetrical and asymmetrical ethers (including O-heterocycles) with an increased molecular complexity. Likewise, ester-to-ether catalytic reductions and hydrogenative alcohol etherifications with CO2 to dialkoxymethanes and other acetals, albeit in less extent, have undergone important advances, too. In this Review, an update of the recent progresses in the area of catalytic reductive alcohol etherifications using carbonyl-based compounds and CO2 have been described with a special focus on organic synthetic applications and catalyst design. Complementarily, recent progress made in catalytic acetal/ketal-to-ether or ester-to-ether reductions and other related transformations have been also summarized.

Selective catalytic synthesis of short chain oxymethylene ethers by a heteropoly acid – a reaction parameter and kinetic study

Oxymethylene ethers (OME) are considered as a low-emission additive or replacement to diesel fuel. They can by efficiently produced in a catalytic process using heteropoly acids as catalyst.

A Perspective on Biofuels Use and CCS for GHG Mitigation in the Marine Sector

The greenhouse gas (GHG) emissions of the marine sector were around 2.6% of world GHG emissions in 2015 and are expected to increase 50%–250% to 2050 under a “business as usual” scenario, making the decarbonization of this fossil fuel-intensive sector an urgent priority. Biofuels, which come in various forms, are one of the most promising options to replace existing marine fuels for accomplishing this in the short to medium term. Some unique challenges, however, impede biofuels penetration in the shipping sector, including the low cost of the existing fuels, the extensive present-day refueling infrastructure, and the exclusion of the sector from the Paris climate agreement. To address this, it is necessary to first identify those biofuels best suited for deployment as marine fuel. In this work, the long list of possible biofuel candidates has been narrowed down to four high-potential options—bio-methanol, bio-dimethyl ether, bio-liquefied natural gas, and bio-oil. These options are further evaluated based on six criteria—cost, potential availability, present technology status, GHG mitigation potential, infrastructure compatibility, and carbon capture and storage (CCS) compatibility—via both an extensive literature review and stakeholder discussions. These four candidates turn out to be relatively evenly matched overall, but each possesses certain strengths and shortcomings that could favor that fuel under specific circumstances, such as if compatibility with existing shipping infrastructure or with CCS deployment become pivotal requirements. Furthermore, we pay particular attention to the possibility of integrating deployment of these biofuels with CCS to further reduce marine sector emissions. It is shown that this aspect is presently not on the radar of the industry stakeholders but is likely to grow in importance as CCS acceptability increases in the broader green energy sector.

Dehydrogenative Coupling of Methanol for the Gas-Phase, One-Step Synthesis of Dimethoxymethane over Supported Copper Catalysts

Oxymethylene dimethyl ethers (OMEs), CH3-(OCH2)n-OCH3, n = 1-5, possess attractive low-soot diesel fuel properties. Methanol is a key precursor in the production of OMEs, providing an opportunity to incorporate renewable carbon sources via gasification and methanol synthesis. The costly production of anhydrous formaldehyde in the typical process limits this option. In contrast, the direct production of OMEs via a dehydrogenative coupling (DHC) reaction, where formaldehyde is produced and consumed in a single reactor, may address this limitation. We report the gas-phase DHC reaction of methanol to dimethoxymethane (DMM), the simplest OME, with n = 1, over bifunctional metal-acid catalysts based on Cu. A Cu-zirconia-alumina (Cu/ZrAlO) catalyst achieved 40% of the DMM equilibrium-limited yield under remarkably mild conditions (200 °C, 1.7 atm). The performance of the Cu/ZrAlO catalyst was attributed to metallic Cu nanoparticles that enable dehydrogenation and a distribution of acid strengths on the ZrAlO support, which reduced the selectivity to dimethyl ether compared to a that obtained with a Cu/Al2O3 catalyst. The DMM formation rate of 6.1 h-1 compares favorably against well-studied oxidative DHC approaches over non-noble, mixed-metal oxide catalysts. The results reported here set the foundation for further development of the DHC route to OME production, rather than oxidative approaches.

CuZnZr-Zeolite Hybrid Grains for DME Synthesis: New Evidence on the Role of Metal-Acidic Features on the Methanol Conversion Step

The assessment of the catalytic performance of “hybrid” metal/zeolite catalysts (based on FER or MFI structure and CuZnZr metal complexes) in the methanol dehydration step to DME has been studied in this work. The results clearly show that there is an important effect of the interaction between metal and acid sites affecting the acid catalyst performances. Additionally, deactivation, studied by means of a Timo-on-Stream (TOS) test, was affected by the type of zeolite structure used for hybrid catalyst preparation. The decrease in DME selectivity can be attributed to the cooperation of metal and acid sites in the production of different compounds (mainly methyl formate and dimethoxy methane) converting methanol and DME. The presence of these compounds (indicating different reaction pathways active) was found to be dependent on the zeolite structure and on the type of co-precipitation medium (water or ethanol) used to prepare the hybrid catalyst.

Formal C-H Carboxylation of Unactivated Arenes

A formal C-H carboxylation of unactivated arenes using CO2 in green solvents is described. The present strategy combines a sterically controlled Ir-catalyzed C-H borylation followed by a Cu-catalyzed carboxylation of the in situ generated organoboronates. The reaction is highly regioselective for the C-H carboxylation of 1,3-disubstituted and 1,2,3-trisubstituted benzenes, 1,2- or 1,4-symmetrically substituted benzenes, fluorinated benzenes and different heterocycles. The developed methodology was applied to the late-stage C-H carboxylation of commercial drugs and ligands.

Temperature- and pressure-dependent kinetics of the competing C–O bond fission reactions of dimethoxymethane

Under typical shock tube conditions, dimethoxymethane decomposes mainly to give CH₃ + OCH₂OCH₃.

Identifying high-performance catalytic conditions for carbon dioxide reduction to dimethoxymethane by multivariate modelling

In times of a warming climate due to excessive carbon dioxide production, catalytic conversion of carbon dioxide to formaldehyde is not only a process of great industrial interest, but it could also serve as a means for meeting our climate goals. Currently, formaldehyde is produced in an energetically unfavourable and atom-inefficient process. A much needed solution remains academically challenging. Here we present an algorithmic workflow to improve the ruthenium-catalysed transformation of carbon dioxide to the formaldehyde derivative dimethoxymethane. Catalytic processes are typically optimised by comprehensive screening of catalysts, substrates, reaction parameters and additives to enhance activity and selectivity. The common problem of the multidimensionality of the parameter space, leading to only incremental improvement in laborious physical investigations, was overcome by combining elements from machine learning, optimisation and experimental design, tripling the turnover number of 786 to 2761. The optimised conditions were then used in a new reaction setup tailored to the process parameters leading to a turnover number of 3874, exceeding by far those of known processes.

The Synergistic Effect of Acidic Properties and Channel Systems of Zeolites on the Synthesis of Polyoxymethylene Dimethyl Ethers from Dimethoxymethane and Trioxymethylene

A series of zeolites with different topology structures, including SAPO-34, SUZ-4, ZSM-5, USY, MOR, and beta, were used to synthesize polyoxymethylene dimethyl ethers (PODE_n) from dimethoxymethane (DMM) and trioxymethylene (TOM). The influence of acidic properties and channel systems were studied by activity evaluation, characterization, and theoretical calculation. The results confirmed that pore mouth diameter larger than a TOM molecule was an essential prerequisite for the synthesis of PODE_n over zeolites, and the synergistic effect between medium-strong Brønsted acid sites (Brønsted MAS) and the maximal space of zeolites available determined the catalytic performance of all studied zeolites. DMM and TOM were firstly decomposed into methoxymethoxy groups (MMZ) and monomer CH₂O over Brønsted MAS. Subsequently, the steric constraint of the maximum included sphere, with an appropriate size in zeolite channels, can promote the combination of CH₂O and MMZ to form transition species ZO(CH₂O)_nCH₃, which reacted with the methyl-end group to form PODE_n over Brønsted MAS. Moreover, the reaction temperature showed different effects on the product selectivity and distribution, which also mainly depends on the size of the maximum space available in zeolite channels.

Niobium-substituted octahedral molecular sieve (OMS-2) materials in selective oxidation of methanol to dimethoxymethane

The prepared bifunctional Nb-OMS-2 catalysts are promising candidate in partial oxidation of methanol into dimethoxymethane at a lower temperature suggesting that there is an important temperature regime when forming active sites for DMM production.