Microwaves and microreactors: Design challenges and remedies

Abstract Although microwave enhanced chemistry has become an established research topic, a significant knowledge gap exists with respect to the electromagnetic interactions. This paper aims to address this gap, in particular regarding to small and microstructured processing systems. By means of relatively simple demonstrations, key electromagnetics aspects are highlighted, pointing out the restricted control over operating conditions in familiar microwave systems. In response to these limitations, a radically different approach is presented in the shape of the coaxial traveling microwave multichannel reactor concept. Numerical simulations show that this concept enables controlled and optimized microwave processing.

[1]  Howard C. Reader,et al.  Understanding Microwave Heating Cavities , 2000 .

[2]  Angel Díaz-Ortiz,et al.  Microwaves in organic synthesis. Thermal and non-thermal microwave effects. , 2005, Chemical Society reviews.

[3]  James H. Clark,et al.  Controlling selectivity in catalysis: Selective greener oxidation of cyclohexene under microwave conditions , 2008 .

[4]  Nicholas E. Leadbeater,et al.  Batch and Continuous-Flow Preparation of Biodiesel Derived from Butanol and Facilitated by Microwave Heating , 2008 .

[5]  Tom Van Gerven,et al.  On the parametric sensitivity of heat generation by resonant microwave fields in process fluids , 2013 .

[6]  J Jan Meuldijk,et al.  From batch to flow processing: racemization of N‐acetylamino acids under microwave heating , 2009 .

[7]  Ulrich S. Schubert,et al.  Microwave-assisted chemistry : a closer look at heating efficiency , 2009 .

[8]  D. Sanchez-Hernandez,et al.  New approach for the prediction of the electric field distribution in multimode microwave-heating applicators with mode stirrers , 2004, IEEE Transactions on Magnetics.

[9]  Abhaya K. Datye,et al.  Microwave heating of endothermic catalytic reactions: Reforming of methanol , 2002 .

[10]  Nicholas E. Leadbeater,et al.  Microwave-promoted Suzuki coupling reactions with organotrifluoroborates in water using ultra-low catalyst loadings , 2006 .

[11]  Paul Watts,et al.  The application of microreactors for small scale organic synthesis , 2005 .

[12]  A. I. Stankiewicz,et al.  Process Intensification: Transforming Chemical Engineering , 2000 .

[13]  C. Oliver Kappe,et al.  Controlled microwave heating in modern organic synthesis: highlights from the 2004–2008 literature , 2009, Molecular Diversity.

[14]  Abhaya K. Datye,et al.  On the possibility of a significant temperature gradient in supported metal catalysts subjected to microwave heating , 1997 .

[15]  Dominique M. Roberge,et al.  Microreactor Technology: A Revolution for the Fine Chemical and Pharmaceutical Industries? , 2005 .

[16]  Peter Scholz,et al.  Microwave‐Assisted Heterogeneous Gas‐Phase Catalysis , 2004 .

[17]  V. Hessel,et al.  Micromixers—a review on passive and active mixing principles , 2005 .

[18]  Klaus‐Peter Möllmann,et al.  Eier im Wellensalat: Experimente mit der Haushaltsmikrowelle , 2004 .

[19]  Peter Scholz,et al.  Heterogeneous Gas-Phase Catalysis Under Microwave Irradiation—a New Multi-Mode Microwave Applicator , 2004 .

[20]  Andrzej Stankiewicz On the Applications of Alternative Energy Forms and Transfer Mechanisms in Microprocessing Systems , 2007 .

[21]  M. Herrero,et al.  Nonthermal microwave effects revisited: on the importance of internal temperature monitoring and agitation in microwave chemistry. , 2008, The Journal of organic chemistry.

[22]  Xinhua Qi,et al.  Fast transformation of glucose and di-/polysaccharides into 5-hydroxymethylfurfural by microwave heating in an ionic liquid/catalyst system. , 2010, ChemSusChem.

[23]  Xunli Zhang,et al.  Applications of microwave dielectric heating in environment-related heterogeneous gas-phase catalytic systems , 2006 .

[24]  Roger Meredith,et al.  Engineers' Handbook of Industrial Microwave Heating , 1998 .

[25]  Tom Van Gerven,et al.  On the effect of resonant microwave fields on temperature distribution in time and space , 2012 .

[26]  A. Stankiewicz,et al.  Influence of microwave irradiation on a polyesterification reaction , 2009 .

[27]  Tom Van Gerven,et al.  Structure, energy, synergy, time - the fundamentals of Process Intensification , 2009 .

[28]  Dariusz Bogdal,et al.  Microwave-assisted Organic Synthesis - One Hundred Reaction Procedures , 2006 .

[29]  V. Gude,et al.  Optimization of microwave-assisted transesterification of dry algal biomass using response surface methodology. , 2011, Bioresource technology.

[30]  A. Loupy Microwaves in organic synthesis , 2002 .

[31]  Andrzej Stankiewicz,et al.  Opportunities and challenges for process control in process intensification , 2012 .

[32]  Anders Hallberg,et al.  Microwave-accelerated homogeneous catalysis in organic chemistry. , 2002, Accounts of chemical research.

[33]  R. Gedye,et al.  The use of microwave ovens for rapid organic synthesis , 1986 .

[34]  Tom Van Gerven,et al.  On the accuracy and reproducibility of fiber optic (FO) and infrared (IR) temperature measurements of solid materials in microwave applications , 2010 .

[35]  C. Oliver Kappe,et al.  Microwave-assisted cross-coupling and hydrogenation chemistry by using heterogeneous transition-metal catalysts: an evaluation of the role of selective catalyst heating. , 2009, Chemistry.

[36]  Raymond J. Giguere,et al.  Application of commercial microwave ovens to organic synthesis. , 1986 .

[37]  Tom Van Gerven,et al.  Microwave-activated methanol steam reforming for hydrogen production , 2011 .

[38]  Tine Koloini,et al.  Hydrolysis of sucrose by conventional and microwave heating in stirred tank reactor , 1995 .

[39]  Eder J. Lenardão,et al.  Transesterification of castor oil assisted by microwave irradiation , 2008 .

[40]  J Jan Meuldijk,et al.  Vanishing microwave effects : Influence of heterogeneity , 2007 .

[41]  C. Kappe Microwave dielectric heating in synthetic organic chemistry , 2008 .

[42]  Albert Renken,et al.  Microstructured reactors for catalytic reactions , 2005 .

[43]  V. Gude,et al.  Microwave-Assisted Catalytic Transesterification of Camelina Sativa Oil , 2010 .

[44]  Jonathan D. Moseley,et al.  A Comparison of Commercial Microwave Reactors for Scale-Up within Process Chemistry , 2008 .

[45]  M. J. Cocero,et al.  A predictive approach in modeling and simulation of heat and mass transfer during microwave heating. Application to SFME of essential oil of Lavandin Super , 2012 .

[46]  A. Loupy,et al.  Reactivity and selectivity under microwaves in organic chemistry. Relation with medium effects and reaction mechanisms , 2001 .

[47]  J. Bladel,et al.  Electromagnetic Fields , 1985 .

[48]  Qiong Xu,et al.  Microwave-assisted hydrolysis of crystalline cellulose catalyzed by biomass char sulfonic acids , 2010 .

[49]  Nicholas E. Leadbeater,et al.  Exploring the Scope for Scale-Up of Organic Chemistry Using a Large Batch Microwave Reactor , 2010 .

[50]  O. Shishkin,et al.  Beneficial energy-efficiencies in the microwave-assisted vacuum preparation of polyphosphoric acid , 2011 .

[51]  Reyes Mallada,et al.  Fast microwave synthesis of Pt-MFI zeolite coatings on silicon micromonoliths: application to VOC catalytic combustion , 2012 .

[52]  J. Clark,et al.  Energy Efficiency in Chemical Reactions: A Comparative Study of Different Reaction Techniques , 2005 .

[53]  D. Pozar Microwave Engineering , 1990 .

[54]  Wm. Curtis Conner,et al.  Kinetics of furfural production by dehydration of xylose in a biphasic reactor with microwave heating , 2010 .

[55]  Volker Hessel,et al.  Organic Synthesis with Microstructured Reactors , 2005 .

[56]  James H. Clark,et al.  Novel synthetic methodologies for fluorination and perfluoroalkylation , 2000 .

[57]  A. Loupy,et al.  A tentative rationalization of microwave effects in organic synthesis according to the reaction medium, and mechanistic considerations , 2001 .