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Dimethoxymethane (DMM), a diesel blend fuel, is being researched with high interest recently due to its unique fuel properties. It is commercially produced via a two step-process of methanol oxidation to make formaldehyde, followed by its condensation with methanol. This study presents a one-pot method of DMM synthesis from methanol mediated carbon dioxide hydrogenation over novel heterogeneous catalysts. The effect of catalyst pore structure was investigated by synthesizing 3 wt% Ru over novel hierarchical zeolite beta (HBEASX) and comparing against Ru doped commercial zeolite beta (CBEA) and desilicated hierarchical zeolite beta (HBZDS). The results showed that 3%Ru/HBEASX provided the best activity for DMM production due to its large average pore size. It also showed the decisive role of SiO2/Al2O3 molar ratio, with SiO2/Al2O3 = 75 providing the highest DMM yield of 13.2 mmol/gcat.LMeOH with ca. 100% selectivity. The activity of 3%Ru/HBEAS3 after 5 recycle steps demonstrated the reusability of this catalyst.

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 DMM1-2 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.

A new Mo-Sn catalyst prepared by hydrothermal method was used for the synthesis of dimethoxymethane (DMM) from methanol oxidation. The catalyst with low Mo content can achieve low-temperature oxidation of methanol to DMM with high selectivity. The influence of Mo content on the structure and the catalytic performance of the catalyst was investigated. It was found that Mo1Sn10 catalyst showed the best catalytic performance under the conditions of 140°C and atmospheric pressure, the methanol conversion was 14.2%, and the selectivity of DMM reached 88.9% without the formation of COx during the reaction process. The catalysts were characterized by XRD, Raman, FT-IR, XPS, NH3-TPD and H2-TPR. The results showed that the catalysts with different Mo content had obvious differences in structure and performance. Lower Mo content was more conducive to the formation of Mo5+ and MoOx, and the resulting changes in acidity and redox properties were the important reasons for the excellent performance of the catalysts.

Catalytic behaviors of bimetallic catalysts-alloys of zirconium with vanadium, molybdenum, and iron was investigated in the oxidative dehydrogenation of methanol. The conditions for the formation of the catalyst’s active surface were revealed. The conversion of methanol into formaldehyde, dimethyl ether, and dimethoxymethane on bimetallic catalysts was studied. The characterization of catalysts was performed by XRD, XPS, and SEM. It was shown that the activity of samples increases after О2 + Н2 treatment and was associated with segregation of the active components of alloys (V, Mo) on the surface of catalysts and realization of their optimal oxidation state under catalysis conditions.

Tuning the selective sorption features of microporous organic networks is of great importance for subsequent applications in gas uptake and hiding, while it is snore attractive in terms of being both time and cost effective to realize these optimizations without using functional groups in the core and linker. "Knitting" is one of the easiest and most used method to obtain a broad scope of hyper-crosslinked polymers on a large scale from aromatic structures that do not contain functional groups for polymerization. By the use of Knitting method, a hypercrosslinked covalent ultramicroporous organic polymer was obtained via stepwise process from using triazatruxene (TAT) as core -a planar indole trimer- through anhydrous FeCl3 catalyzed Friedel-Crafts alkylation using dimethoxybenzene as a linker. The resulting microporous polymer, namely TATHCCP was completely identified by analytical and spectral techniques after examined for gas properties (CO2, CH4, O-2, CO, and H-2) and selectivity (CO2/N-2, CO2/O-2, for CO2/CO and CO2/CH4) up to 1 bar and increased temperatures (273 K, 296 K and 320 K). Although it has a relatively low (Brunauer-Emmett-Teller) BET specific surface area around 557 m(2)/g, it was seen to have a high CO2 capture capacity approaching 10% wt. at 273 K. In accordance with (ideal adsorbed solution theory) IAST computations, it was revealed that interesting selectivity features hitting up to 60 for CO2/N-2, 45 for CO2/O-2, 35 for CO2/CO, 13 for CO2/CH4 at lower temperatures revealed that the material has much better selectivity values than many ITCP (hyper-crosslinked polymer) derivatives in the literature even from its most similar analog dimethoxymethane derivative TATHCP, which has a surface area of 950 m(2)/g.

This work investigates the reaction kinetics of the thermal decomposition of dimethoxymethane (DMM) and 1,2-dimethoxyethane (1,2-DME), which are both representative molecules of the promising clean polyether fuels. Pyrolysis experiments are carried out with helium diluted mixtures containing individual fuels in a flow tube at two different pressures of 760 Torr and 30 Torr. By varying the temperature distributions along the flow tube, the resulting species composition is sampled downstream the reactor and analyzed by a photoionization mass spectrometer. A kinetic model, including sub-mechanisms for the thermal decomposition of both fuels, is proposed, which can well characterize important measurements, such as the fuel decomposition reactivity and the speciation of crucial products. Under identical conditions, 1,2-DME exhibits a higher decomposition reactivity than DMM, because of the characteristic C–C bond fission as well as the easier hydrogen abstraction reactions by methyl radical. Some fuel-specific intermediates are observed, including methyl formate in DMM pyrolysis, methyl vinyl ether and methoxy acetaldehyde in 1,2-DME pyrolysis. These species mainly come from fuel radical dissociations following the hydrogen abstractions from the central (–CH2O–) and (–CH2CH2O–) moieties in DMM and 1,2-DME, respectively. The formation of some other intermediates are closely related to the consumption of these fuel-specific species. Particularly, the decomposition of methyl formate produces high concentrations of methanol in DMM pyrolysis. In 1,2-DME pyrolysis, the consumption of methyl vinyl ether and methoxy acetaldehyde brings about the formation of C2 oxygenated intermediates such as acetaldehyde, ethenol and ketene. Higher concentrations of unsaturated C2 (ethylene and acetylene) and larger hydrocarbon intermediates present in 1,2-DME pyrolysis, due to the existence of C–C bond in the fuel molecule.

Chemical kinetics of plasma assisted oxidation of dimethyl ether was investigated by photoionization molecular beam mass spectrometry (PI-MBMS) and kinetic modeling. A series of hydrocarbon and oxygenated intermediates, especially some fuel-specific oxygenated intermediates including methyl formate, ethyl methyl ether and dimethoxymethane, were identified by the measured mass spectra and photoionization efficiency (PIE) curves. The quantification results displayed two main change patterns of species mole fractions with increasing oxygen, indicating the different dominating formation pathways. In addition to the oxygenates, C1 and C2 hydrocarbon intermediates were observed at low temperatures in the DME/O2/Ar and DME/Ar plasma systems, while the formation of these intermediates usually occurs at temperatures higher than 800 K in the thermal oxidation of DME. A kinetic model containing gas-phase reactions and plasma reactions was developed. The model analysis suggests that both hydrogen abstractions and plasma reactions involving electron/Ar*/O(1D)/Ar+ contribute to the fuel consumption. The subsequent reactions of the resulting CH3OCH2, CH3O and CH3 lead to the yield of the observed hydrocarbons and oxygenates. The experimental results together with kinetic modeling indicate that the fuel and fuel radical may decompose into methyl radical, oxygen atom and formaldehyde directly, which account for the under prediction of formaldehyde and the observation of oxygenates with moderate concentrations in the DME/Ar plasma.

Oxymethylene ethers (OME) are considered as a low-emission additive or replacement to diesel fuel. They can be synthesized by different routes based on C1 platform chemicals in different oxidation states. The challenge is to tune the acidic catalyst for the condensation reaction to a selectivity for a certain oligomeric fraction (OME3–5) for optimal fuel properties. Herein, we report the use of heteropoly acids that showed an outstanding activity and selectivity for the production of the respective OME fraction under very mild reaction conditions. Trioxane and dimethoxymethane (OME1) were used as substrates which are both products of the methanol value-added chain. Reaction parameters such as catalyst/substrate ratio and temperature could be reduced considerably due to a high catalytic activity and selectivity. Kinetic data were obtained experimentally and modelled to estimate the reaction rate, activation energy and pre-exponential factor as a solid basis for further reaction engineering.

Synthetic dimethoxymethane (DMM) is a promising fuel or blend component as it offers outstanding combustion characteristics. DMM production from hydrogen (H2) and carbon dioxide (CO2) is technically feasible with established technology but results in a low overall process efficiency. Recent research in catalyst development has increased DMM yield significantly and new reaction pathways have been proposed. Yet, it remains unknown how the achievements in catalyst development affect process performance. To close this gap, we analyze processes based on five reaction pathways regarding exergy efficiency, production cost, and climate impact. As the pathways have different technology readiness levels, we develop a methodology that ensures consistent boundary conditions and model detail between pathways. The methodology enables a hierarchical optimization-based process design and evaluation. The results show that the non-oxidative (i.e., reductive, dehydrogenative, and transfer-hydrogenative) pathways consume stoichiometrically less H2 not only than the established and oxidative pathway, but also less than most other electricity-based fuels (e-fuels). The higher resource efficiency of these pathways increases process exergy efficiency from 75% to 84%; production cost (2.1$ Ldiesel-eq.−1) becomes competitive to other e-fuels; and the impact on climate change reduces by up to 92% compared to fossil diesel, if renewable electricity is utilized. Whereas the reductive pathway may already enable a sustainable production of DMM with only little catalyst improvements, the dehydrogenative and transfer-hydrogenative pathways still require a higher DMM selectivity and methanol conversion, respectively. With considerable catalyst improvements, a maximum exergy efficiency of 92% and minimum production cost of 2.0$ Ldiesel-eq.−1 are achievable. Our analyses show: With the non-oxidative pathways, the high potential of DMM is no longer restricted to its outstanding combustion characteristics but extended to its production., Energy & Environmental Science, 14 (7), ISSN:1754-5692, ISSN:1754-5706

Pyrolysis and low-temperature oxidation of dimethoxymethane (methylal, MeOCH2OMe) play an important role in the ignition of blended diesel fuels, but the underlying mechanisms are still debated. In these kinetic models, bimolecular hydrogen abstraction or unimolecular C–O bond fission are considered as the primary initial steps, while MeOCH2OMe isomerization is sometimes disregarded. In this work, we investigate the pyrolysis of MeOCH2OMe combining imaging photoelectron photoion coincidence spectroscopy with vacuum ultraviolet (VUV) synchrotron radiation and CBS-QB3 theoretical calculations to unveil reaction paths and energetics. In the mass spectrum of MeOCH2OMe, pyrolysis products and radical intermediates were observed at m/z 15 (CH3), 28 (CO), 29 (HCO), 30 (H2CO), 31 (CH2OH), 32 (CH3OH), 45 (CH3OCH2), and 75 (H-loss from methylal). Only the m/z 45 and 75 ions are found to be dissociative photoionization products of MeOCH2OMe, the other mass spectral peaks are attributed to ionization of the neutral MeOCH2OMe pyrolysis products. The m/z 31 peak was assigned to the methoxy radical in the previous studies. However, our photoion mass-selected threshold photoelectron spectrum (ms-TPES) confirms that it originates from dissociative photoionization of the primary pyrolysis fragment methanol. Based on the experimental and computational results, a thermal decomposition mechanism of MeOCH2OMe is proposed. Here, H-migration precedes the production of methoxymethylene (CH3OCH) and methanol, while dimethyl ether and formaldehyde are probably formed in multi-step processes, too. The sequential dissociation of CH3OCH and of dimethyl ether yields enhanced m/z 15, 28 and 29 signals at high temperature. Rate constants have been calculated to confirm the dominant role of MeOCH2OMe isomerization and to help improve predictive combustion models.

Levulinate is one of the high added-value biomass-derived chemicals that is primarily produced from hexoses in cellulose and hemicellulose. Producing levulinate from pentoses in hemicellulose that is extensively distributed in biomass is still highly challenging. In this study, biomass materials and carbohydrates (including cellulose, xylan, glucose, fructose, and xylose) were collaboratively converted into levulinates efficiently over various zeolites with ethanol/dimethoxymethane as cosolvents. The key process for converting pentoses into levulinates is the synthesis of intermediates (furfural) into alkoxy methyl furfural via electrophilic substitution or their conversion into furfuryl alcohol via in situ hydrogenation. The substitution was achieved by the synergic effect between bifunctional catalysts and cosolvents, which promotes conversion of furfural into alkoxy methyl furfural via the electrophilic addition of alkoxy methyl radicals. Hydrogenation of furfural into furfuryl alcohol was impelled by the cooperative process between in situ generated H-donor from alcohol solvents and zeolite catalysts. Moreover, a favorable yield of 21.05 mol % of levulinates was achieved by simultaneous and collaborative conversion of cellulose and hemicellulose with the one-pot process using ethanol/dimethoxymethane as a cosolvent and the zeolite with B and L acid sites as a catalyst.

A simple and highly efficient method for the preparation of 1,1-dimethoxymethane (DMM) is described using a molecularly defined NNN-Ni(II) complex (2 mol %). The reaction proceeds via the direct condensation reaction of methanol with paraformaldehyde under mild and neutral conditions. This atom-economical approach provides DMM in excellent yields in shorter reaction time. A simple and highly efficient method for the preparation of 1,1-dimethoxymethane (DMM) is described using a molecularly defined NNN-Ni(II) complex (2 mol%). The reaction proceeds via the direct condensation reaction of methanol with paraformaldehyde under mild and neutral conditions. This highly atom-economical approach provides DMM in excellent yields in shorter reaction time.

Ammonia (NH3) is considered a promising carbon-neutral fuel, with a high hydrogen content, that can diversify the global energy system. Blending ammonia with a highly reactive fuel is one possible ...

A composite material Fe–V/g-C3N4 prepared by impregnation achieved an efficient performance for heterogeneously catalytic oxidation of methanol to dimethoxymethane (DMM) and poly(oxymethylene) dimethyl ethers (POM) by O2 oxidant in batch reactor, exhibiting 34.3% conversion and > 99.0% selectivity to DMM and POM. However, a pioneered strategy for tuneable synthesis of DMM and POM was realized by controlling the reaction time. The experimental results revealed that FeVO4 and V2O5 nanoparticle crystallizes served as the active sites and higher specific areas 29.3–51.9 m3/g for the catalysts were jointly responsible for the high activity. Besides, the catalyst could be easily recovered and effectively reused. A composite material Fe–V/g-C3N4 with higher specific area exhibited efficient performance for heterogeneously catalytic oxidation of methanol to dimethoxymethane (DMM) and polyoxymethylene dimethyl ether (POM) in batch reactor using O2 oxidant. Moreover, a pioneered strategy for tunable synthesis of DMM and POM was realized by controlling the reaction time. The catalyst was easily recovered and had excellent recycle lifetime and stability.

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 t...

Acidic zeolites are considered a kind of efficient catalysts in the synthesis of polyoxymethylene dimethyl ethers (PODEn) with the fomula of CH3O–(CH2O)n–CH3, a promising green diesel fuel or additive from methanol derivatives; however, the crucial parameters that determine PODEn yield and reaction mechanism over zeolite catalyst remains rather ambiguous. In this work, the relationship between the catalytic performance of HZSM-5 zeolite and Si/Al ratio and reaction temperature was revealed through PODEn synthesis from dimethoxymethane (DMM) and trioxymethylene (TOM). The results indicate that the Si/Al ratio and reaction temperature are interdependent in determining the PODEn yield; High Al HZSM-5 zeolites( Si/Al ≤ 50) show the highest PODE2-8 selectivity and yield only at 70–90 °C, whereas low Al zeolites (Si/Al ≥ 109) possess the better activity to PODE2–8 at 70–150 °C. The reaction mechanism was then investigated through in-situ IR characterization and DFT calculation. The important intermediates ZO-CH2OCH2OCH2OH, ZOCH2OCH3 and ZO(CH2O)nCH3 (ZOH: HZSM-5 zeolite) were detected by In situ IR spectra during the exposure of HZSM-5 to TOM, DMM and co-feed. DFT calculations further verified above reaction intermediates and elucidated the reaction elementary steps. Reaction mechanism was proposed as follows: the Bronsted acidic sites provided by Al–OH of HZSM-5 zeolite promote the dissociation of TOM to monomer CH2O and transform DMM to ZOCH2OCH3 and CH3OH; Next, the CH2O species react with short chain ZO(CH2O)nCH3, forming long chain ZO(CH2O)nCH3; After that, the PODEn products are formed by sealing ZO(CH2)nOCH3 with CH3OH. Ultimately, the difference of catalytic performance resulting from the effect of Si/Al ratio and reaction temperature, based on the proposed mechanisms, was given a logical explanation. The detailed reaction mechanism in the synthesis of polyoxymethylene dimethyl ethers from dimethoxymethane and trioxymethylene over HZSM-5 zeolite were investigated through a series of in-situ IR characterization and DFT calculation. Subsequently, the difference of catalytic performance resulting from the effect of Si/Al ratio and reaction temperature, was given a possible explanation.

Laminar flame speeds of dimethyl ether and dimethoxymethane at pressures from 1 to 5 bar and initial temperatures from 298 to 373 K were determined experimentally using a constant volume spherical vessel and a heat flux burner setup. This study is the first to report dimethoxymethane laminar flame speeds at a pressure higher than 1 bar. Using these experimental data along with data available in the literature, a new kinetic model for the prediction of the oxidation behavior of dimethyl ether and dimethoxymethane in freely propagating and burner stabilized premixed flames, in shock tubes, rapid compression machines, flow reactors, and a jet-stirred reactor has been developed. The experimental results from the present work and literature are interpreted with the help of the derived kinetic model. This newly developed reaction mechanism considers the redox chemistry of NOx to accommodate the influence of the oxygen level on the onset of fuel conversion and interconversion of NO and NO2. The current model suggests that an increased O2 level promotes the HO2 production, which in turn leads to the formation of OH radicals, which promotes the combustion of the fuel/air mixture under lean conditions. The increase of OH radical concentrations is mainly via the NO/NO2 interconversion reaction channel, NO+HO2=NO2+OH, NO2+H=NO+OH, CH3OCH3+NO2=CH3OCH2+HONO, followed by the thermal decomposition of HONO. This work extends the kinetic database and helps to improve the understanding of dimethyl ether and dimethoxymethane combustion behavior. The kinetic model presented in this work can serve as a base model for hydrocarbons and oxygenated fuels higher than C2.

Ignition delay times (IDTs) of fuel-rich CH4/dimethoxymethane (DMM)/air mixtures (ϕ = 2 and 10) were measured in a high-pressure shock tube at a pressure of 30 bar and compared to simulations based on reaction mechanisms for DMM from literature. Additionally, IDT of DMM/air mixtures were measured at similar conditions in a wide range of equivalence ratios (ϕ = 0.5, 1, and 2). Those mechanisms that predict the IDTs of DMM within the experimental uncertainties also predict the IDTs of the fuel-rich CH4/DMM/air mixtures very well although they were not designed for these conditions. For the measurements at ϕ = 10, product gas samples were extracted from the shock tube test section at around 14–24 ms after arrival of the reflected shock wave by a fast-opening valve and analyzed with gas chromatography. Besides CO, H2, and H2O, ethane, ethylene, acetylene, benzene, propene and toluene were observed as main reaction products.

Catalytic steam reforming of dimethoxymethane (DMM) to hydrogen-rich gas was successfully performed using structured CuO-ZnO/ƞ-Al2O3/FeCrAl catalysts. The catalysts containing on their surface both acidic and copper-based sites were active and selective for DMM steam reforming to hydrogen-rich gas with low (

A nitrogen-riched porous organic polymer named as BA-M was synthesized by co-polymerization of benzene and aniline monomers with dimethoxymethane as cross-linker through a simple Friedel-Crafts alkylation reaction. A series of the porous organic polymer supported bimetallic PdAg nanoparticles catalysts were developed for the selective hydrodeoxygenation of lignin-derived species including vanillin, isoeugenol and so on. The remarkable catalytic performance with 100% conversion of vanillin and 100% selectivity to p-creosol were achieved over the Pd9Ag1/BA-M catalyst at mild condition (low hydrogen pressure and temperature). The Pd9Ag1/BA-M catalyst also showed excellent recyclability with the catalytic activity and selectivity being well preserved after six catalytic recycles. The interaction between metal nanoparticles and porous organic polymer support, together with the nitrogen species in porous organic polymer support were primarily responsible for the excellent catalytic performance of bimetallic PdAg catalysts.

A 1,10-phenanthroline based polymer named PPPhen(i.e., polymer from pyrene 1,10-phenanthrolin) was prepared by the Friedel-Crafts reaction of 1,10-phenanthroline and pyrene cross-linked with dimethoxymethane. The related Pd catalyst Pd@PPPhen was prepared by supporting Pd nanoparticles(NPs) on the PPPhen material. PPPhen and Pd@PPPhen were characterized by means of scanning electron microscopy(SEM), transmission electron microscopy, N2 adsorption-desorption, Fourier-transform infrared and X-ray photoelectron spectroscopy analyses. The results showed that PPPhen polymer was highly porous and that the phenanthroline group can enhance the stability of the Pd nanoparticles. Pd@PPPhen also exhibited good catalytic activity in the aerobic oxidation of alcohols to aldehydes and ketones, and Pd@PPPhen was recyclable with durable activity and retentive structures.

Poly(oxymethylene dimethyl ethers) (OMEn, CH3O˗(CH2O)n˗CH3) with the appropriate chain length n = 3–5 are discussed as alternative diesel fuels due to their applicability for direct blending with diesel fuel in slightly modified diesel engines. This group of oxygenates have regained much interest as they significantly reduce soot formation during combustion, which is reflected in their large-scale pilot plant production. This work focuses on a favorable route for an efficient synthesis of OME3-5 from dimethoxymethane and trioxane at ambient pressure under mild reaction conditions. A detailed study was conducted on the catalytic performance of both methanesulfonic acid and the commercial solid acid Deloxan® as environmentally benign catalysts and promising replacements for sulfuric acid. For this, special focus on the influences of different reaction parameters (e.g. temperature, molar educt ratio, reaction time and pressure) was investigated herein. Hence, methanesulfonic acid (3.5 wt%) and Deloxan® (1.7 wt%) were found to be suitable catalysts for the anhydrous synthesis of OME with an OME3-5 selectivity of 32.7 wt% and 30.0 wt%, respectively. Furthermore, synthesis of OMEs catalyzed by either methanesulfonic acid or Deloxan® was found to follow Schulz-Flory distribution denoting a sequential OME chain-propagation.

Dimethoxymethane (OME1) is an important chemical and has vast applications. However, the current commercial method to produce this chemical suffers high exergy loss. In this study, we demonstrate a...

Herein, a simple method was developed for the first time to pretreat sulfonic acid resin-based catalysts using different solvents (such as n-hexane, toluene, acetone, methanol, dimethyl sulfoxide, and sulfolane), and the as-treated resins were applied in DMM carbonylation. Except for sulfolane, the treatment solvents with a higher dipole moment resulted in a higher turnover number (TON) but lower DMM conversion and MMAc selectivity. SAresin-sulfolane-393 K exhibited excellent activity and stability for 50 h with an STY of 3.15 mmolMMAc (gcat h)−1 and nearly 100% MMAc selectivity. The Arrhenius plot of SAresin-sulfolane-393 K was generated from the reaction rate data at various temperatures, and the apparent activation energy was calculated to be 18.39 kJ mol−1. Karl Fischer analysis, in situ FT-IR analysis of CO adsorption, and static CO adsorption method indicated that the residual H2O in SAresin was significantly reduced and the CO adsorption capacity was obviously enhanced. The nitrogen adsorption–desorption isotherms, FT-IR spectra, and SEM and EDX-mapping images of SAresin-sulfolane-393 K proved that a larger average pore diameter and pore volume were generated, and sulfolane indeed entered the resin and changed the chemical composition of SAresin. The FT-IR spectra of the pyridine pre-adsorbed samples and Hammett acidity function (H0) confirmed that SAresin-sulfolane-393 K exhibited a stronger acid strength. The unusual activity and stability of SAresin-sulfolane-393 K are attributed to its stronger acid strength, low H2O content and excellent CO adsorption capability.

Methyl methoxyacetate (MMAc) is a significant chemical product and can be applied as a gasoline and diesel fuel additive. This study aimed to achieve the industrial production of MMAc via dimethoxymethane (DMM) carbonylation. The effects of industrial DMM sources, reaction temperature, water content, pretreatment temperature, reaction pressure and time, the ratio of CO to DMM and recycle times were systematically investigated without any solvent. The conversion of DMM was 99.98% with 50.66% selectivity of MMAc at 393 K, 6.0 MPa reaction pressure, with the ratio of CO to DMM of only 1.97/1. When water was extracted from the DMM reactant, the MMAc selectivity significantly rose to 68.83%. This resin catalyst was reused for more than nineteen times in a slurry phase reactor and continuously performed for 300 h without noticeable loss of activity in a fixed bed reactor, displaying excellent stability. The mixed products were successfully separated by distillation, and 99.18% purity of MMAc was obtained. Therefore, the reported DMM carbonylation to MMAc process has an excellent basis for industrial application.

The direct access to dimethoxymethane (DMM) from CO2/H2 in MeOH is an attractive approach, but more active, selective, and robust catalyst systems are still desirable for an application of this system. Herein, we present the performance enhancing effect of additives on ruthenium-triphos catalyst systems for CO2 hydrogenation to DMM. In the presence of PPh3, functioning as both additional ligand and precursor for Lewis-acidic phosphonium salts, increased turnover numbers for DMM are achieved. Moreover, PPh3 significantly diminishes catalyst degradation via carbonylation to cationic [RuH(CO)2(triphos)]OTf, which remains an active species in the synthesis of DMM. Catalyst recycling over up to five runs with minimal loss in catalyst performance underlines the robustness of the system. Both, the recyclability of the system and the suppression of catalyst deactivation pathways encourage for application in sustainable continuous processes.

Catalytic decomposition of oxygenated compounds of C1 chemistry into hydrogen rich gas was studied over Pt/CeO2-ZrO2 catalyst. In particular, formic acid, methanol, dimethyl ether and dimethoxymethane were decomposed under atmospheric pressure into hydrogen-rich gas at temperatures below 450 oC. Challenges and benefits of each reaction in producing hydrogen-rich gas for fuel cell feeding are discussed

Four oxygenated fuels: ethanol (EtOH), dimethyl carbonate (DMC), dimethoxymethane (DMM) and polyoxymethylene dimethyl ether (PODE3) were blended with Jet A2 to investigate the sooting behaviour of the fuel mixtures. The smoke point was measured using wick-fed laminar diffusion flames as per the ASTM D1322 standard. The oxygen extended sooting index (OESI) was calculated to determine the sooting tendency of each mixture. Colour-ratio pyrometry and differential mobility spectrometry were used to measure the soot volume fraction (fv) and particle size distribution (PSD). The addition of oxygenated fuels caused a strong reduction in sooting tendency (i.e. OESI) at low blend strengths (5%) and a weaker linear reduction at higher blend strengths (10% and 20%). Each mixture showed a similar reduction at a given mole fraction of oxygenated fuel. The OESI broadly correlated with the soot volume fraction and particle size measurements. Increasing blend strengths resulted in smaller particles at the tip of the flame. The average particle size at the tip was influenced by the oxygen content but not the molecular structure of the oxygenated fuels, whereas the soot volume fraction in the wings was influenced by both the molecular structure of the oxygenated fuels and the oxygen/carbon ratio of the mixture. For the first time, fv and PSD have been reported for flames produced using Jet A2 blends in an ASTM D1322 lamp. The ability to relate data gathered using the ASTM D1322 standard for the sooting behaviour of different mixtures is going to be increasingly important as the aviation industry seeks to switch to sustainable fuels. National Research Foundation (NRF) This research was supported by the National Research Foundation, Prime Ministers Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme. Y. R. Tan acknowledges financial support provided by Fitzwilliam College Cambridge, Trinity College Cambridge and the Cambridge Trust. M. Kraft gratefully acknowledges the support of the Alexander von Humboldt Foundation.

The potential of dimethyl ether (DME) and dimethoxymethane (DMM), representatives of the attractive oxymethylene ether (OME) alternative fuel family, are explored here as reactivity enhancers for methane-fueled polygeneration processes. Typically, such processes that can flexibly generate power, heat, or chemicals, operate under fuel-rich conditions in gas turbines or internal combustion engines. To provide a consistent basis for the underlying reaction mechanisms, it is recognized that speciation data for the DME/CH4 fuel combination are available for such conditions while such information for the DMM/CH4 system is largely lacking. In addition, it should be noted that a detailed speciation study in flames, i.e., combustion systems involving chemistry and transport processes over a large temperature range, is still missing in spite of the potential of such systems to provide extended species information. In a systematic approach using speciation with electron ionization molecular-beam mass spectrometry (EI-MBMS), we thus report, as a first step, investigation of six fuel-rich premixed flames of DME and DMM and their blends with methane with special attention on interesting chemicals. Secondly, a comprehensive but compact DME/DMM/CH4 model (PolyMech2.1) is developed based on these data. This model is then examined against available experimental data under conditions from various facilities, focusing preferentially on elevated pressure and fuel-rich conditions. Comparison with existing literature models is also included in this evaluation. Thirdly, an analysis is given on this basis, via the extensively tested PolyMech2.1 model, for assumed polygeneration conditions in a homogeneous charge compression ignition (HCCI) engine environment. The main interest of this model-assisted exploration is to evaluate whether addition of DME or DMM in a polygeneration process can lead to potentially useful conditions for the production of syngas or other chemicals, along with work and heat. The flame results show that high syngas yields, i.e., up to similar to 78% for CO and similar to 35% for H-2, can be obtained in their burnt gases. From the large number of intermediates detected, predominantly acetylene, ethylene, ethane, and formaldehyde show yields of 2.1-4.4% (C-2 hydrocarbons) and 3.4-8.7% (CH2O), respectively. Also, methanol and methyl formate show comparably high yields of up to 0.6-6.7% in the flames with DMM, which is 1-2 orders of magnitude higher than in those with DME as the additive. In the modeling-assisted exploration of the engine process, the PolyMech2.1 model is seen to perform at significantly reduced computational costs compared to a recently validated model without sacrificing the prediction performance. Promising conditions for the assumed polygeneration process using fuel combinations in the DME/DMM/CH4 system are identified with attractive syngas yields of up to 77% together with work and heat output at exergetic efficiencies of up to 89% with DME. (C) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Catalytic partial oxidation (PO) of dimethoxymethane (DMM) to syngas was investigated in a fixed-bed continuous flow reactor under ambient pressure and at 250–500 °C over Pt-, Rh- and Ru-supported on Ce0.75Zr0.25O2–δ catalysts. The Pt catalyst was found to be the most active and selective. It provided complete conversion of DMM to gas mixture containing ˃ 60 vol% of H2 and CO at 400 °C, GHSV = 10,000 h−1 using a reaction mixture: DMM:O2:N2 = 28.6:14.3:57.1 (vol%).

The main purpose of this work was to demonstrate that steam reforming of methylal (dimethoxymethane, MA), even at low steam-to-MA ratios, can be used for thermal recuperation of the energy of inter...

A series of H-ZSM-5 zeolites were prepared by changing the NaOH content in the synthesis gel and their catalytic performance in the vapor-phase carbonylation of dimethoxymethane (DMM) to produce methyl methoxyacetate (MMAc) was investigated. The results indicate that the H-ZSM-5 zeolite prepared with the synthesis gel containing 0.81% NaOH exhibits the highest catalytic activity in the vapor-phase DMM carbonylation. Various characterization results of nitrogen sorption, 27Al NMR, NH3-TPD and Py-FTIR illustrate that both the medium-strong Bronsted acid sites and mesoporous volume are crucial factors in promoting the carbonylation of DMM over H-ZSM-5, which can be effectively regulated by changing the NaOH content in the synthesis gel. The increase of medium-strong Bronsted acid sites can raise the DMM conversion by providing more active acid sites, whereas the mesopores can improve the selectivity to MMAc by shortening the product diffusion path, weakening the steric constraints and suppressing the side reactions. The density functional theory calculation further illustrates that ZOCH2OCH3 intermediate is formed upon the decomposition of DMM on H-ZSM-5; based on this observation, a possible reaction mechanism for the formation of MMAc was then proposed.

The role of Lewis and Brønsted acid sites and their potential synergy remains ambiguous for the production of polyoxymethylene dimethyl ethers (OME), which are suitable as a Diesel substitute. Here, this synergistic effect was investigated by using a series of beta polymorph A (BEA) zeolites with various degrees of Brønsted and Lewis acidity. Lewis acidity was introduced in dealuminated zeolites by Sn grafting in dichloromethane. These sites were only active in paraformaldehyde decomposition, OME growth, and acetalization. The Brønsted acid sites arising from bridging hydroxyl groups were active for all reaction steps, and notably for trioxane ring-opening and dissociation to formaldehyde (FA), which did not occur on the Lewis acid sites. Presence of both Lewis and Brønsted acid sites led to a four-fold increase in turnover frequency and a significant decrease of byproduct formation compared with the parent zeolite during OME synthesis from dimethoxymethane and trioxane. The synergistic effect between both types of acid sites is explained by FA insertion on Lewis acid sites leading to OME growth. Interaction between tetrahedral Sn and the carbonyl group of FA resulted in an activated carbonyl bond, which was likely the initial step for insertion of FA into OME.

Kinetic research concerning fuel blends of ethers or dithers and larger alkanes at low temperatures is extremely scarce. In this work, a study of the oxidation of dimethoxymethane (DMM)/n-heptane fuel blends (neat n-heptane, 25/75, 50/50, neat DMM) was performed using an atmospheric pressure jet-stirred reactor over the temperature range of 500–1100 K, at a residence time of 2.0 s, at three equivalence ratios (0.5, 1.0, and 2.0), and at a constant fuel inlet mole fraction of 0.005 (with high dilution in argon). The reliability of the newly built JSR setup was validated against literature data. A chemical kinetic model capable of describing the low temperature chemistry of the fuel blends was constructed. The effect of using AramcoMech 1.3 and AramcoMech 2.0, respectively, as the base-mechanism has been tested and some important reactions such as Ḣ +O2 (+M) HȮ2 (+M), have been found to be responsible for their different performances. Not unexpectedly, the reactivity of DMM is remarkably enhanced in the fuel blends and correspondingly, that of n-heptane is inhibited. To quantify the degree to which the reactivity of n-heptane is inhibited, an inhibiting coefficient was introduced. It is interesting that the correlation between the inhibiting intensity and equivalence ratio is non-monotonic. Rate of production analysis was conducted to investigate the chemical interaction effect on their respective decomposition pathways at lower temperatures. Kinetic analysis combined with the experimental observations indicate that the rate coefficients for H-abstraction reactions by ȮH from DMM were overestimated. Possible modifications to the reaction rate of this reaction type were suggested, leading to a better prediction. Three intermediate representatives were discussed in detail to elucidate the chemical interactions between the two fuel components.

In this study (Part II), the oxidation of dimethoxymethane (DMM) is investigated and a detailed chemical reaction model developed for a comprehensive description of both high- and low-temperature oxidation processes. The sub-mechanism of DMM is implemented using AramcoMech2.0 as the base mechanism. Rate coefficients are based on analogies with those for dimethyl ether, diethyl ether, and n-pentane oxidation. Furthermore, theoretical studies from recent works are also included in the present model and new calculations for the dissociation kinetics of Q ˙ OOH radicals have been carried out at the CCSD(T)/CBS(aug-cc-pVXZ; X = D, T) // B2PLYP-D3/6-311 + + G(d,p) level of theory. For validation, new ignition delay time experiments have been performed in a shock tube (ST), a rapid compression machine (RCM), and in a laminar flow reactor covering a wide range of conditions (p = 1–40 bar, T = 590–1215 K, φ = 1). In addition, the kinetic model is validated against laminar burning velocities, jet-stirred reactor, plug flow reactor and further ST and RCM experimental datasets from the literature. Pathway and sensitivity analyses were used to identify critical reaction pathways in the DMM oxidation mechanism. These show that the reactivity of DMM at intermediate temperatures is controlled by the branching between pathways initiated on the primary or secondary fuel radical. While primary fuel radicals eventually lead to chain branching, secondary fuel radical consumption is controlled by fast β-scission over a wide range of temperatures, which inhibits reactivity.

This work reports product composition and kinetics of the catalytic decomposition of methylal (dimethoxymethane, C3H8O2), which is a good hydrogen vector. To the best of our knowledge, this is the first report on methylal reforming by decomposition over supported metal catalysts for fueling an internal combustion engine (ICE) while using the hot exhaust gases to heat the reactor. The decomposition activities of commercial Pt/Al2O3, Ni/Al2O3, and laboratory-synthesized Rh/Al2O3 were investigated. While the activities of Pt and Ni catalysts were promising, Rh exhibits poor activity. Pt catalyst exhibits appreciable methylal conversion and yields primarily a mixture of H2, CO, and DME above 300 °C. Ni produces a mixture of H2, CO, and methane. Isothermal studies revealed that both catalysts undergo deactivation evident by an initial decline in H2 and CO production rates while DME production was stable. Coke deposition was observed on both catalysts, but the TPO revealed 5 times more coke on Ni catalysts than...

Trace dimethoxymethane (DMM) was formed by aldol condensation of formaldehyde with methanol in industrial propene oxide production via a hydrogen peroxide (HPPO process). Probing the behaviour of catalytic action in oxidative cleavage reaction of C C bond of alkene is urgently needed for the development of production technology. Using 1-hexene as a probe, the oxidation of alkenes with H2O2 was investigated via titanium silicalite-1 (TS-1) catalysis. Influences of solvent, temperature, additives and H2O2/alkene molar ratio on alkene conversion and oxidation product distribution were studied. Interestingly, besides the epoxidation products, aldehydes were also produced by double-bond oxidative cleavage in this system. The results showed that ethyl acetate as solvent was favor for the generation of aldehyde, but the additives [Na2HPO4·12H2O (A) and NaH2PO4(B)] could significantly inhibit it. These phenomena indicated that the catalytic oxidative cleavage of 1-hexene in TS-1/H2O2 system was probably based on an addition and cleavage oxidation process in an acidic environment.

A composite material VOx/g-C3N4 was prepared and its composition and structure was characterized by FT-IR, XRD, SEM, TEM and XPS. The results showed that VOx was grafted on g-C3N4 surface with molecularlevel dispersion via V or O atoms interacting with the characteristic groups on g-C3N4 surface. The highly dispersed VOx/g-C3N4 exhibited effectively catalytic activity and high selectivity for oxidation of methanol into methoxymethane (DMM), giving 44.9 mol/(molV·h) TOF and 95.2% selectivity of DMM. The dependence of catalytic activity on the surface properties and preparation procedure of the catalyst, reaction conditions and kinetics, and the stability of the catalyst were explored. Also, the in situ DRIFTS spectra of methanol adsorption on the VOx/g-C3N4 surface and effect of O2 on the adsorption, as well as the reaction mechanism were discussed.

Due to the increasing demand for formaldehyde as a building block in the chemical industry as well as its emerging potential as feedstock for biofuels in the form of dimethoxymethane and the oxymethylene ethers produced therefrom, the catalytic transformation of carbon dioxide to the formaldehyde oxidation state has become a focus of interest. In this work, we present novel ruthenium complexes with hetero-triphos ligands, which show high activity in the selective transformation of carbon dioxide to dimethoxymethane. We substituted the apical carbon atom in the backbone of the triphos ligand platform with silicon or phosphorus and optimized the reaction conditions to achieve turnover numbers as high as 685 for dimethoxymethane. The catalytic systems could also be tuned to preferably yield methyl formate with turnover numbers of up to 1370, which in turn can be converted into dimethoxymethane under moderate conditions.

The fuel used in this study, DMM is an oxygen additive containing 42.5% oxygen by weight and dissolved in diesel fuel, also known as methyl alcohol or Dimethoxymethane (CH3-O-CH2-O-CH3). DMM, which is a colorless liquid, shows chemical characteristics of gas-liquid and is also used as a diesel fuel component. In this study, five mixtures were added to the common diesel fuel at DMM addition rates of 2.5, 5, 7.5, 10 and 12.5% by volume. A single cylinder, four strokes, DI diesel engine was used as the test engine. Experimental data were also collected at 24 engine speed-load conditions operating in steady state. The purpose of this experiment was to study the effect of the addition ratio of oxidized fuel mixed in diesel fuel on engine power and exhaust performance. When compared with the common diesel fuel, the exhaust of Smoke was substantially reduced in all DMM mixing ratios. These results indicate that DMM can be an effective blend of diesel fuel and is an environmentally friendly alternative fuel. This study also shows that smoke and NOx emissions can be reduced at the same time through the application of oxygen fuel and EGR.

In this work, ionic liquid (IL) as green solvent was first proposed for capturing methanol and dimethoxymethane (DMM) gases released in the fuel synthesis process. The hydrophilic IL [EMIM][BF4] was selected from 192 kinds of ILs by the COSMO-RS model. The separation mechanism was revealed at the molecule level in combination with the quantum chemistry calculation. The vapor-liquid equilibrium (VLE) data for the binary mixture of methanol (or DMM) and [EMIM][BF4] were experimentally obtained and compared with the prediction of UNIFAC-Lei model. It was found that the popular UNIFAC-Lei model can predict the VLE of the methanol + [EMIM][BF4] and DMM + [EMIM][BF4] mixtures well. Moreover, the methanol and DMM capture experiments using [EMIM][BF4] as absorbent were carried out, demonstrating the good separation performance. Furthermore, a rigorous equilibrium EQ stage model including the UNIFAC-Lei model parameters was built for simulating and optimizing the methanol and DMM capture processes using [EMIM][BF4] and the conventional benchmark solvent triethylene glycol (TEG) as absorbents at industry level. This work confirmed that capturing methanol and DMM gases with ILs is a typical process intensification method.