Synthesis Of Methyl Methacrylate Research Articles

Influence of pore structure on catalytic performance of Cs-Zr/SiO2 catalyst for methyl methacrylate synthesis from methyl propionate and formaldehyde

Methyl methacrylate (MMA) synthesis via aldol condensation of methyl propionate with formaldehyde over Cs-based supported catalysts is intensively investigated, while the effect of their pore structures on catalytic performance still lacks in-depth understanding. Herein, series of Cs-Zr/SiO2 catalysts with different pore structures were prepared for this aldol condensation. The physicochemical characteristics of as-prepared Cs-Zr/SiO2 catalysts were characterized using physical N2 adsorption–desorption isotherms and CO2–/NH3-TPD. In addition, the impact of pore structure on mass transfer, adsorption, and desorption of reactants and products was studied through in situ DRIFTS. The results show that the acid and base site densities elevated with the increasing pore volume. The mass transfer of reactants and products could be promoted with increasing pore size, while their adsorption energies exhibited a volcanic trend. As a result, the Cs-Zr/SiO2 catalysts having average pore diameter of 12–18 nm and acid-base balance was considered as the optimal candidate for MMA production.

Elucidating the Promotional Effects of the Al Element on the Catalytic Performance of Al–Cs/SiO2 for Methyl Methacrylate Synthesis via One-Step Aldol Condensation

Elucidating the Promotional Effects of the Al Element on the Catalytic Performance of Al–Cs/SiO₂ for Methyl Methacrylate Synthesis via One-Step Aldol Condensation

Promotional effect of Ti on catalytic performance of Cs/Ti-SiO2 for conversion of methyl propionate and formaldehyde to methyl methacrylate

Synthesis of methyl methacrylate (MMA) by aldol condensation of methyl propionate (MP) with formaldehyde (FA) has received researchers’ attention in recent years. Herein, a kind of acid-base bi-functional Cs/Ti-SiO2 was developed for the conversion of MP and FA to MMA. A series of Cs/Ti-SiO2 samples with different acid-base properties were prepared by changing the loading amount of Cs and Ti elements and characterized using XRD, BET, FT-IR, DR UV–vis, SEM, TEM, XPS, CO2/NH3-TPD, O2-TPO, py-IR, and TGA. The introduction of Ti species could significantly regulate the acidity and affect the surface structure of catalyst, facilitating the activation of reactants and aldol reaction effectively. The relationship between the acid-base properties and catalytic activity was correlated, which revealed the crucial role of weak and medium acid sites in this transformative process. The production of MMA was optimized by using response surface methodology (RSM) based on the Box-Behnken design (BBD) approach. As a result, 62.8 % yield of MMA with selectivity of 75.6 % could be achieved at optimal reaction conditions. The catalyst would suffer deactivation from carbon deposition, which could be easily regenerated by simple thermal treatment without any decrease in initial activity during 600 h time-on-stream. Kinetic studies unraveled the activation energy of aldol condensation was 112.2 kJ/mol.

Comprehensive analysis on the economy and energy demand of pressure-swing distillation and pervaporation for separating waste liquid containing multiple components

A large amount of waste liquids containing methanol/acetone/water mixtures are produced in the synthesis of methyl methacrylate (MMA). Under the advocacy of green chemical industry, it is urgent to develop an efficient, economic and energy-saving mixture separation process. Through thermodynamic azeotropic behavior and pressure sensitivity analysis, pressure-swing distillation was determined and the optimal separation pressure of each column in the process was obtained. Due to the composition of waste liquids produced were quite different in MMA production, the pressure-swing distillation separation process was designed to fully achieve the accurate waste liquids treatment. Taking the total annual cost (TAC) as the target, the sequential iteration method was used to optimize the process, and the impact of composition on economy was compared. In order to further realize the energy-saving of the separation process, the pervaporation membrane module was introduced to pretreat the waste liquid in the pressure-swing distillation. The results showed that the TAC of the coupling process was 46% higher than that of the pressure-swing distillation process, and the thermodynamic efficiency was 30% higher. This study provides waste liquid treatment technology for enterprises and analyzes its economic and energy efficiency, which has reference significance for the development of coupled separation technology.

Kinetic and thermodynamic studies on direct synthesis of methyl methacrylate from methyl propionate and methanol catalyzed by highly efficient cobalt complex at mild conditions

Methyl methacrylate (MMA) typically produced from the petroleum-based ethylene or isobutene selective oxidation route is a significantly important chemical widely used in industrial manufacture. Herein, an innovative and highly efficient liquid-phase catalytic system, cobalt complex catalyzed O2-interrupted hydrogen borrowing pathways, was developed for direct synthesis of MMA from methyl propionate and methanol at mild conditions, considering the problems of poor selectivity, rapid catalyst deactivation, and formaldehyde polymerization existed in one-step aldol reaction of methyl propionate with formaldehyde at 350–380 °C. The yield and selectivity of MMA could reach up to 50.2% and 81.8% at 60 °C and 1 atm. Thermodynamic calculations and analysis for this novel transformative process were conducted to confirm the feasibility and reasonability for MMA production at low temperature (below 100 °C). On the basis of the reaction networks proposed according to the experimentally detected products, studies on the kinetic informatics of this new process were conducted. The formaldehyde oxidation, aldol condensation of methyl/t-butyl propionate with formaldehyde and transesterification of t-butyl propionate/methacrylate with methanol are first-order dependent on their reactant concentrations. While the methanol dehydrogenation and transesterification of methyl propionate/methacrylate with t-BuOK are first-order dependent on the concentration of only methanol and t-BuOK. With the understanding of kinetic behavior of these reaction steps composed, the global kinetic model was established to describe this catalytic system and the corresponding parameters including pre-exponential factor and activation energy were calculated. The oxidative dehydrogenation of methanol to formaldehyde, with the highest activation energy of 84 kJ/mol, was the kinetic-relevant step, while the aldol condensation of methyl propionate with formaldehyde showed the lowest energy of 36 kJ/mol.

Synthesis, characterization, catalytic performance of magnetically recoverable nano-Au/MCeOx (M: Fe, Co and Ni) in direct oxidative esterification of methacrolein and methanol

Series of magnetic metal-doped cerium oxide (MCeOx, M = Fe, Co and Ni) were synthesized and applied to support nano-gold (Au) as catalyst for synthesis of methyl methacrylate (MMA) through gas-liquid-solid three-phase oxidation esterification of methacrolein (MAL) and methanol (MeOH). Hydrothermal synthesis method was applied for MCeOx preparation and deposition-precipitation method was for nano-Au supported catalyst. The catalysts were characterized through XRD, H2-TPR, NH3-TPD, FT-IR, TG, BET, TEM-EDS and VSM. Results showed that Au/FeCeOx had strong magnetic properties and could be easily separated by external magnetism. Moreover, the doping of Fe could improve the redox properties and acidic sites of the catalyst. Catalyst performances were evaluated in a micro batch reactor. 5% - Au/FeCeOx allowed the highest reaction activity to be observed with MAL conversion of 80.2% and MMA selectivity of 96.1%. Surface catalytic reaction mechanism on Au/CeO2 was established and transition states of oxidative esterification were obtained using density functional theory (DFT). Magnetically recoverable nano-Au/FeCeOx catalysts maintain stable activity after 5 cycles, which makes it a promising catalyst for industrial application.

Production of citramalate in Escherichia coli by mediating colonic acid metabolism and fermentation optimization

Citramalic acid (citramalate) is important for the chemical synthesis of methylmethacrylate, a bulk monomer used for manufacturing biodegradable polymers. Escherichia coli strains have been engineered for the biological production of citramalate since a rare mutant of citramalate synthase was invented as a mesophilic catalyzer to form the chemical. However, acidic byproducts are routinely excreted by E. coli host cells during fermentation, which could significantly reduce the carbon conversion efficiency of biosynthetic chemicals, including citramalate. Herein, an unusual mutant called S17–3 was reported, and this mutant demonstrated superb recovery efficacy from glucose to citramalate and secreted a very low level of fermentation byproducts during the fermentative production of citramalate. However, S17–3 tends to produce a large amount of colonic acid (CA). Genetically manipulating the regulators involved in CA synthesis revealed that the deletion of rcsD could significantly improve the citramalate titer. Fed-batch fermentation under optimized conditions led to a maximum titer of 46.2 g/L citramalate accumulated in the broth, with a conversion efficiency of 0.80 g citramalate per gram glucose and a close-to-the-theoretical mole transversion efficiency (mol/mol) of 0.97. This study facilitates the development of a practical bioproduction of citramalate using E. coli strains.

Synergic effect between gold and vanadate substituted hydroxyapatite support for synthesis of methyl methacrylate by one-step oxidative esterification

• Au/HVP catalyst displays excellent performance for oxidative esterification. • The high selectivity derives from the good capacity of activation of oxygen. • O 2 was adsorbed and activated with the synergic effect of gold with the support. • The active sites are located at the interfacial sites between gold and the support. Synthesis of methyl methacrylate (MMA) via direct oxidative esterification from methacrolein (MAL) and methanol (MeOH) is of great significance in chemical industry. Supported gold catalysts are considered as one of the most potential candidates for this reaction but suffer from low activity and deactivation issue. Herein, by modulating the phase structure of hydroxyapatite (HAP) with different cations and anions, a synergic effect between gold and vanadate substituted hydroxyapatite (HVP) support for the synthesis of MMA was discovered. In direct oxidative esterification, among the evaluated catalyst/support systems, Au/HVP catalyst displays the best performance and unprecedented stability, which acts as one of the best-performing gold catalysts for oxidative esterification. Various characterizations such as X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM), transmission electron microscope (TEM) and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of CO were conducted to disclose the structural and electronic property of the catalysts. Through in-situ FT-IR spectra of MAL and MeOH, the substrate was proved to be easily transformed on Au/HVP catalyst to ester. Besides, the presence of O 2 was found to facilitate the adsorption of MAL. The results of temperature programmed desorption (TPD) of O 2 implied that gold particles together with HVP support is promotional for activation and dissociation of oxygen, leading to good activity and high selectivity.

Efficient Synthesis of Methyl Methacrylate by One Step Oxidative Esterification over Zn-Al-Mixed Oxides Supported Gold Nanocatalysts

Methyl methacrylate (MMA) is an important monomer in fine chemicals. The synthesis of MMA by one-step oxidative esterification from methacrolein with methanol over a heterogeneous catalyst with high activity, selectivity and stability is highly desirable. Herein, Zn-Al-hydrotalcites (HTs)-supported atomically precise Au25 nanoclusters with different molar ratios of Zn2+/Al3+ were prepared and used as the precursors for this reaction. They exhibited good performances in comparison with the gold catalysts prepared by the deposition precipitation method. The structural and electronic properties were evaluated by various characterization technologies, including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) of CO adsorption, X-ray photoelectron spectroscopy (XPS), and CO2 temperature-programmed desorption (TPD). The combined characterization results suggested that the adsorption property of gold and the basicity of the catalyst contributes to their high activities. Substrates extended experiments and stability tests implied the potential application of Zn-Al-mixed oxides supported gold catalysts, which paves a new way for supported gold catalyst in the one-step oxidation esterification reaction.

Continuous-Flow Methyl Methacrylate Synthesis over Gallium-Based Bifunctional Catalysts

This paper reports on a systematic study on the catalytic gas-phase synthesis of methyl methacrylate (MMA) by means of the hydroxymethylation and dehydration of methyl propionate (MP) with formalde...

One-step synthesis of methyl methacrylate from methyl propionate and methanol under mild condition

In recent years, coal-based one-step synthesis of methyl methacrylate (MMA) stimulated researchers’ interest due to the over-capacity of coal chemical industry. However, the high reaction temperature, low yield and selectivity, catalyst deactivation due to carbon deposition, and volatilization and polymerization of formaldehyde have been the challenging problems in this field. In this work, the cascade reactions of methanol dehydrogenation to formaldehyde, aldol condensation between formaldehyde and methyl propionate, and O2-inteerrupted hydrogenation of MMA were resolved via construction of mild and efficient cobalt complex catalyzed interrupted hydrogen borrowing system. Thus, one-step synthesis of MMA from methyl propionate and methanol in liquid phase at 80 °C with yield and selectivity of 25.7% and 92.6% was realized. The cobalt complex activation and methanol dehydrogenation mechanisms were investigated with nuclear magnetic resonance (NMR) characterization, and the C–H bond activation and breakage of methanol was identified as the rate-controlling step through kinetic isotopic effect experiments, which provided new research direction for coal-based synthesis of MMA.

A Novel Design of Methyl Methacrylate Synthesis Process with Low CO2 Emission

Methyl methacrylate (MMA) is an important raw material for synthesising polymethyl methacrylate, plastic modifier, and surface coating. In this paper, an optimum “energy saving and low emission” process is proposed for MMA production. MMA is synthesised from ethylene and synthetic gas generated from coal chemical looping gasification (CLG), which can largely reduce CO2 emission. Firstly, the reaction mechanism of coal CLG is investigated using molecular dynamics simulation. Secondly, to verify the feasibility of the process, the steady-state simulation of MMA production process is carried out by Aspen Plus. Finally, based on the steady-state simulation results, one control scheme is verified with Aspen Dynamics to strictly control the purity of MMA.

Theoretical Investigation of the Heterojunction Effect on the Catalytic Activity and Selectivity of an Au@NiO Core–Shell Catalyst in Aerobic Oxidation

Numerous experimental reports have addressed the advantages of the Au@NiO core-shell catalyst in the synthesis of methyl methacrylate. However, its high activity toward the oxidation of 1-methoxy-2...

Methyl Methacrylate Synthesis: Thermodynamic Analysis for Oxidative Esterification of Methacrolein and Aldol Condensation of Methyl Acetate

Methyl methacrylate (MMA) as a specialty monomer of polymers has motivated industry to develop clean and sustainable technologies for its production. Herein, a comprehensive thermodynamic analysis ...

Fe-Modified Cs–P/γ-Al2O3 Catalyst for Synthesis of Methyl Methacrylate from Methyl Propionate and Formaldehyde

To meet the increasing demand for methyl methacrylate, a series of Fe modified Cs–P/γ-Al2O3 catalysts were developed through the impregnation method and tested for the aldol condensation of methyl ...

Ionic‐Liquid‐Modified Porous Au/CeMnOx Nanorods for Methyl Methacrylate (MMA) Synthesis via Direct Oxidative Esterification

AbstractPorous MnCeOx solid solutions nanorods (PN‐MnCeOx) with different pore sizes were prepared using different carbon chain lengths ionic liquids (C10mimCl, C12mimCl and C14mimCl). Series of novel catalysts with nano‐Au supported on the PN‐MnCeOx, were synthesized and applied to oxidative esterification of aldehydes (benzaldehyde derivatives or methacrolein – MAL) to esters. Catalytic performance was evaluated in batch reactor and the relatively optimum catalyst was screened out. Kinds of characterization methods, such as XRD, TEM, XPS and BET, were applied to analyze crystal plane, microstructure, specific surface area, and porous structure of the catalysts and the structure‐activity relationship could be reasonably explained. The cyclic stability of the catalyst was also tested more than 7 times using MAL and methanol for methyl methacrylate synthesis via one step oxidative esterification.

Efficient and catalyst free synthesis of acrylic plastic precursors: methyl propionate and methyl methacrylate synthesis through reversible CO2 capture

Single solvent based, room temperature and catalyst free synthesis of acrylic plastic precursors namely methyl propionate and methacrylate was performed via reversible CO2 capture.

Kinetic scheme and rate constants for methyl methacrylate synthesis occurring via the radical–coordination mechanism

Two kinetic schemes of the bulk radical–coordination polymerization of methyl methacrylate initiated by the benzoyl peroxide–ferrocene system are considered from the standpoint of formal kinetics. The most likely kinetic scheme is the one that includes the reactions characteristic of classical radical polymerization and, additionally, reactions of controlled radical polymerization proceeding via the Organometallic Mediated Radical Polymerization mechanism, a reaction generating a coordination active site, and a chain propagation reaction in the coordination sphere of the metal. The temperature dependences of the rate constants for the reactions of this kinetic scheme at temperatures typical of commercial poly(methyl methacrylate) production (313–353 K) have been determined by solving the inverse kinetic problem.

SBA-15 Supported Cesium Catalyst for Methyl Methacrylate Synthesis via Condensation of Methyl Propionate with Formaldehyde

SBA-15 supported metal-doped cesium ion catalysts were prepared by the impregnation method and characterized by N-2 adsorption-desorption, XRD, FT-IR, and SEM and TEM. The characterization results indicated that the ordered hexagonal mesoporous structure of the support remained intact after incorporating cesium. Stepwise TPD of NH3 and CO2 was used to estimate the strength and the number of surface acid and base sites, respectively. The effects of Cs-loading, sources of cesium cation, and template concentration on the physicochemical properties and catalytic performance were investigated. The catalytic performance was evaluated by the gas-phase condensation reaction of methyl propionate with formaldehyde in a fixed-bed reactor. Compared with the amorphous SiO2 catalyst, at similar Cs loading (ca. 15 wt %) SBA-15 catalyst exhibited better selectivity and yield.

Synthesis of Methyl Methacrylate by Aldol Condensation of Methyl Propionate with Formaldehyde Over Acid–Base Bifunctional Catalysts

Supported cesium catalysts with various carriers (SiO2, Al2O3, TiO2, MgO) were prepared and characterized by X-ray diffraction, BET nitrogen adsorption-desorption, NH3 and CO2-TPD methods and thermogravimetric analysis. Experimental results showed that the Zr-Mg-Cs/SiO2 catalyst exhibited moderate activity for aldol condensation of methyl propionate with formaldehyde (FA) to produce methyl methacrylate. Though the activity of Zr-Mg-Cs/SiO2 catalyst decreased with the time-on-stream, the deactivated catalyst was completely regenerated by calcination. The catalyst was regenerated 16 times and total operation time was over 500 h, its activity was identical with that of the fresh catalyst.