Catalysis for the synthesis of methacrylic acid and methyl methacrylate

Abstract

Methyl methacrylate (MMA) is a specialty monomer for poly methyl methacrylate (PMMA) and the increasing demand for this monomer has motivated industry to develop clean technologies based on renewable resources. The dominant commercial process reacts acetone and hydrogen cyanide to MMA (ACH route) but the intermediates (hydrogen cyanide, and acetone cyanohydrin) are toxic and represent an environmental hazard. Esterification of methacrylic acid (MAA) to MMA is a compelling alternative together with ethylene, propylene, and isobutene/t-butanol as feedstocks. Partially oxidizing isobutane or 2-methyl-1,3-propanediol (2MPDO) over heteropolycompounds to MAA in a single-step is nascent technology to replace current processes. The focus of this review is on catalysts and their role in the development of processes herein described. Indeed, in some cases remarkable catalysts were studied that enabled considerable steps forward in both the advancement of catalysis science and establishing the basis for new technologies. An emblematic example is represented by Keggin-type heteropolycompounds with cesium and vanadium, which are promising catalysts to convert isobutane and 2MPDO to MAA. Renewable sources for the MMA or MAA route include acetone, isobutanol, ethanol, lactic, itaconic, and citric acids. End-of-life PMMA is expected to grow as a future source of MMA.

A Review of the Biotechnological Production of Methacrylic Acid

“…Currently, MMA is produced via one of several processes from a few key petrochemical feedstocks as illustrated in Figures 1A-G. Over 65% of MMA is produced via the Acetone CyanoHydrin (ACH) route, developed in the 1930's ( Figure 1D) (Nagai and Ui, 2004). The use of toxic hydrogen cyanide, as well as concentrated acids are a primary concern with the ACH route, as is the negative impact of significant waste (ammonium bisulfate) generation and treatment (Nagai and Ui, 2004;Mahboub et al, 2018). A competitive route, Direct Oxidation (and similar processes), relies on isobutylene as a feedstock (Figure 1B) and is primarily commercial in Asia (Nagai and Ui, 2004;The Chemical Engineer, 2008;Mahboub et al, 2018).…”

“…The use of toxic hydrogen cyanide, as well as concentrated acids are a primary concern with the ACH route, as is the negative impact of significant waste (ammonium bisulfate) generation and treatment (Nagai and Ui, 2004;Mahboub et al, 2018). A competitive route, Direct Oxidation (and similar processes), relies on isobutylene as a feedstock (Figure 1B) and is primarily commercial in Asia (Nagai and Ui, 2004;The Chemical Engineer, 2008;Mahboub et al, 2018). Concerns over safety, costs, and the environmental impact of the ACH route have driven efforts to find alternative routes to produce MMA (Adom et al, 2014).…”

Progress in Reaction Mechanisms and Reactor Technologies for Thermochemical Recycling of Poly(methyl methacrylate)

“…An advantage of PMMA, compared to PC, is that it does not contain bisphenol A, which is a hazardous toxic chemical [35]. The most used process by European producers of the monomer MMA is the acetone cyanohydrin route [24,36]. This process can be subdivided in three consecutive steps.…”

“…The methacrylamide sulfate is subsequently brought into contact with an excess of aqueous methanol, resulting in the formation of MMA and ammonium sulfate. Normally, sulfuric acid can be recycled or neutralized with ammonia, producing ammonium sulfate as co-product which can be, together with the formed ammonium sulfate from the MMA production, sold to the fertilizer market [36].…”

A study of the oxidehydration of 1,2-propanediol to propanoic acid with bifunctional catalysts

“…Amongst the various compounds which can be synthesized from 1,2-PD, eg, propionaldehyde by dehydration [11][12][13][14], propanol [15], and pyruvaldehyde [16], and propanoic acid (PAC) [17][18][19], the latter might be the intermediate for the synthesis of bio-based methacrylic acid (MAA) and methylmethacrylate (MMA), the monomer for polymethylmethacrylate [20][21][22]. The glycerol-to-MAA pathway would thus include the following steps: Scheme 1.…”