Novel Process Windows for Enabling, Accelerating, and Uplifting Flow Chemistry

Abstract

Novel Process Windows make use of process conditions that are far from conventional practices. This involves the use of high temperatures, high pressures, high concentrations (solvent-free), new chemical transformations, explosive conditions, and process simplification and integration to boost synthetic chemistry on both the laboratory and production scale. Such harsh reaction conditions can be safely reached in microstructured reactors due to their excellent transport intensification properties. This Review discusses the different routes towards Novel Process Windows and provides several examples for each route grouped into different classes of chemical and process-design intensification.

Chemical reaction engineering, process design and scale-up issues at the frontier of synthesis: Flow chemistry

“…Some basic issues of process design and scale-up, or better numbering up, have been taken into account by Hessel et al [6].…”

“…Hazardous reactants such as phosgene, HCN and HN3 can be more safely managed in flow regime than in batch, also developing their in-situ synthesis [6]. Examples of organic synthesis under harsh conditions in the pharmaceutical industry, such as nitrations and organometallic reactions, are critically reviewed by Kockmann and Roberge [146].…”

Novel synthesis of thick wall coatings of titania supported Bi poisoned Pd catalysts and application in selective hydrogenation of acetylene alcohols in capillary microreactors

“…Microreactors have many advantages over traditional large-scale chemical reactors: the small dimensions of microreactors facilitate mass-and heat-transfer, small reaction volume allows the handling of hazardous or expensive chemicals safely and high-pressure reactions to be carried out with inexpensive equipment, hence significant process intensification is possible with microreactor technology. [8][9][10][11][12][13][14] In heterogeneous catalytic reactions however, the advantages of microreactors are offset by the problem of catalyst introduction into the reactor. A convenient laboratory practice to use packed-bed reactors, i.e.…”

“…27 This method was applied to obtain a 5-20 μm thick coating inside shorter (0.3 m) reactors 28 or a thin coating (90 nm) inside 10-m long reactors. 23,29 Another derivative of the dip-coating method, the fill-and-dry method, can be used to obtain [10][11][12][13][14][15][16][17][18][19][20] μm thick catalytic coatings inside short reactors. [30][31][32] However, the essential component of these methods, solvent evaporation, requires years to remove solvent from a longer (5 m) reactor according to estimations performed using Stefan's equation, 33 Fig.…”

Beyond Organometallic Flow Chemistry: The Principles Behind the Use of Continuous-Flow Reactors for Synthesis

“…This concept of using unusual reaction conditions is also called Novel Process Windows, coined by Hessel. [12][13][14] The use of microreactor technology further provides enhanced process safety, high control over the reaction conditions, and increasing throughput by controlled scalability. According to a detailed investigation of Roberge et al, 50% of the reactions in the 4 pharmaceutical and fine chemical industry could benefit from a continuous process.…”