Commercialisation of a Novel Methyl Methacrylate Process – Catalyst Design and Development

2012 Spring Symposium

David W. John­son
Lucite Inter­na­tion­al UK Ltd

Abstract — A brief out­line of Lucite International’s new “Alpha” methyl methacry­late tech­nol­o­gy is described includ­ing process scale up and the first exploita­tion in Sin­ga­pore in late 2008. The tech­nol­o­gy was devel­oped from 0.5g/h lab scale to 500g/h pilot and thence direct­ly to 12te/h com­mer­cial scale. The plant was com­mis­sioned from first intro­duc­tion of chem­i­cals to 100% rate with­in 3 weeks and cur­rent­ly oper­ates at over 16te/h with excep­tion­al reli­a­bil­i­ty.

Two cat­alyt­ic steps are key to the tech­nol­o­gy. In the first, car­bon monox­ide, eth­yl­ene and methanol are react­ed in solu­tion with a nov­el pal­la­di­um phos­phine cat­a­lyst which gives methyl pro­pi­onate in 99.9+% selec­tiv­i­ty in a con­tin­u­ous process at ppm lev­el pal­la­di­um con­cen­tra­tions at 100C and 10bar total pres­sure. The cat­a­lyst activ­i­ty and life is very sen­si­tive to oper­at­ing con­di­tions. After exten­sive process devel­op­ment, activ­i­ties of 15,000 moles/mole Pd/h and life of >1x107moles methyl propionate/mole Pd are rou­tine­ly achieved on the com­mer­cial plant.

The sec­ond stage cat­a­lyst, com­posed of caesium/zirconia/silica reacts methyl pro­pi­onate with formalde­hyde at 330C and 1–2barg to form methyl methacry­late (MMA) and water. The selec­tiv­i­ty is about 93% to MMA based on methyl pro­pi­onate and over 80% on formalde­hyde fed. The pre­sen­ta­tion describes some of the steps in devel­op­ment of the cat­a­lyst includ­ing com­par­isons with cat­a­lysts for sim­i­lar process dis­closed by com­peti­tors. A dis­cus­sion of the mech­a­nism of for­ma­tion of MMA and byprod­ucts is made in terms of sur­face reac­tions between reac­tants and prod­ucts. A 2-site mod­el is pro­posed involv­ing both strong­ly basic and hydrox­ylic, weak­ly acidic sites. Reac­tions catal­ysed in byprod­uct for­ma­tion include decar­boxy­la­tions, com­bined con­den­sa­tion-decar­boxy­la­tions, hydride trans­fers and acid catal­y­sis. Lucite has found that com­pet­i­tive cat­a­lysts have the wrong bal­ance of acid­i­ty and basic­i­ty and result gen­er­al­ly in high lev­els of hydride trans­fer and acid catal­y­sis prod­ucts.

Speaker’s Biog­ra­phy: The author has a BA (Nat­ur­al Sci­ences, Chem­istry) from Oxford Uni­ver­si­ty a PhD in radi­a­tion chem­istry and car­ried out post­doc­tor­al research in LEED/XPS/UPS before join­ing ICI Ltd in 1977. With­in ICI he worked ini­tial­ly on nitrate pro­mot­ed sil­ver eth­yl­ene oxide cat­a­lysts fol­lowed by 4 years in ICI’s New Sci­ence Group study­ing the struc­ture of nov­el zeo­lites syn­the­sised by ICI co-work­ers. Since 1990 he has worked in the area of MMA process design and led the explorato­ry research team which defined the Alpha process and cur­rent­ly leads Lucite’s (for­mer­ly ICI Acrylics) chem­istry team. His cur­rent inter­ests are process improve­ment for the Alpha tech­nol­o­gy and intro­duc­tion of biotech­nol­o­gy into MMA man­u­fac­ture.