Abstract
Development of active and selective catalysts for the process of obtaining methacrylic acid and methyl methacrylate from methyl propionate, propionic acid and formaldehyde is one of important stages to industrial implementation of this process. In order to solve this problem, we designed catalysts based on oxides of boron and phosphorus that were promoted by oxides of zirconium, tungsten and bismuth with varied content of oxides. The effect of temperature was examined on the conversion of reagents, the selectivity of formation and the yield of methyl methacrylate and methacrylic acid on the created catalysts. With increasing temperature, the conversion increases, the selectivity of formation of acrylates decreases and the total yield of acrylates has the maximum. It was found that without adding methanol, the optimal catalyst by acrylates yield is the one, in which the molar ratio of the ZrO 2 :WO 3 promoters is 0.15:0.15. The total yield of the target products at optimum temperature of 593 K is 52.3 % with the total selectivity of their formation at 96.4 % and the conversion of reagents of 54.2 %. We determined the effect of adding methanol to the reagent mixture. Adding methanol increases the ratio of products MMA/MAA, and the optimal catalyst by the total selectivity of formation of the target products is the one promoted by bismuth oxide with the molar ratio of Bi 2 O 3 /Р 2 О 5 – 0.3, which at a temperature of 593 K provides for the selectivity of formation of acrylates of 100 % with the yield of 33 %. The maximum total singlepass yield of MMA and MAA on this catalyst at a temperature of 623 K is 51.5 %, at the total selectivity of their formation of 91.6 %. However, the share of MMA in products is lower in comparison to the catalyst, promoted by the mixture of tungsten and zirconium oxides.
Highlights
The aim of this work is the development of catalytic systems for obtaining methacrylic acid and methyl methacrylate by the method of compatible condensation of propionic acid and methyl propionate with formaldehyde in the gas phase
The designed B2O3–P2O5/SiO2 catalytic system promoted by ZrO2:WO3=0.15:0.15 allowed us to increase the selectivity of formation of the target products to 96.4 %, which is 31 % higher, and made it possible to carry out the process of condensation of methyl propionate (MP) and PA with FA at a lower optimum temperature of 593 K than in the process without propionic acid, confirming possibility and feasibility of the PA recycling in the process of condensation of MP and FA
Adding methanol to the initial mixture makes it possible to reach total selectivity of methyl methacrylate (MMA) and methacrylic acid (MAA) 100 % on the catalyst promoted by bismuth oxide, which allows for designing of the waste-free process, but with a lower yield of the target products
Summary
Acrylates occupy a prominent place in the industry of organic synthesis. The main area of their use is the fabrication of acrylate polymers, which owing to their valuable technical properties such as transparency, mechanical strength, ductility, thermal resistance have found applications in various spheres of human activity. Existing methods of obtaining acrylate monomers have a number of shortcomings – producing large amounts of by-products of oxidation, formation of toxic wastes, as well as a big number of stages of the process [1, 2]. Papers [10, 11] established that for the process of aldol condensation of MP with FA, the active boron-phosphorus-oxide catalyst was developed, applied on the silica gel, promoted by zirconium oxide (B2O3:P2O5:ZrO2=3:1:0.3), due to the hydrolysis of part of the MP to PA and methanol, the total selectivity of the formation of acrylates is low – 65.4 %. The maximum conversion value of 83 % was obtained at the catalyst, promoted by zirconium and tungsten oxides with the molar ratio ZrO2:WO3 = 0.3:0.3 at a temperature of 683 K
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Eastern-European Journal of Enterprise Technologies
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
