Lithographically fabricated silicon microreactor for in situ characterization of heterogeneous catalysts—Enabling correlative characterization techniques

Abstract

We report on a new modular setup on a silicon-based microreactor designed for correlative spectroscopic, scattering, and analytic on-line gas investigations for in situ studies of heterogeneous catalysts. The silicon microreactor allows a combination of synchrotron radiation based techniques (e.g., X-ray diffraction and X-ray absorption spectroscopy) as well as infrared thermography and Raman spectroscopy. Catalytic performance can be determined simultaneously by on-line product analysis using mass spectrometry. We present the design of the reactor, the experimental setup, and as a first example for an in situ study, the catalytic partial oxidation of methane showing the applicability of this reactor for in situ studies.

Recent Advances in Selective Propylene Oxidation over Bismuth Molybdate Based Catalysts: Synthetic, Spectroscopic, and Theoretical Approaches

“…164 Engeldinger et al 79 used a Linkam reaction cell, which is similar to a fixed-bed reactor, and Zhai et al 38 and Getsoian et al 44 used a pellet reactor for their in situ studies. As the selective oxidation of propylene is performed industrially in fixed-bed reactors and shows spatial gradients of the phases, as described in section 8, optical quartz cuvette reactors, 165 capillary reactors, 166 or microreactors, 167 which allow spatially resolved measurements along the catalyst bed, should be preferred. Figure 11 illustrates an example of spatially resolved XAS measurements in the catalytic bed of a 5% Pt−5% Rh/Al 2 O 3 catalyst during catalytic partial oxidation of methane, performed in a capillary reactor.…”

Silicon microfabricated reactor for operando XAS/DRIFTS studies of heterogeneous catalytic reactions

“…The use of microfluidic and microfabricated reactors which can offer accurate control of process conditions, homogeneous temperature distribution and a distinct flow pattern, has been reported for operando spectroscopic studies under realistic reaction conditions. [39][40][41][42][43][44][45][46][47] Such microreactors are valuable and compact tools for spectroscopic studies 24,39 including Raman, 40,48,49 IR, [50][51][52][53] X-ray diffraction (XRD) 45,54,55 and XAS. 42,45,55,56 Among such reactors, silicon microfabricated reactors have unique advantages due to their high thermal conductivity, chemical inertness and mechanical stability.…”

“…In particular, the transparency of silicon to X-rays and IR beams (also glass for Raman) makes the glass-bonded silicon microreactor ideal for combined operando XAS and DRIFTS studies. 55 In our previous work, a silver sputter-coated microchannel of a silicon-glass microreactor was employed for operando Raman spectroscopic studies of continuous oxidative dehydrogenation of methanol to formaldehyde. 40 The silver sputter-coated microchannel of the microreactor served itself as a catalyst surface and it enabled us to evaluate the effect of temperature and reaction feed composition on the catalyst structure and activity, and to identify reaction intermediates.…”

Microfabricação De Reatores Poliméricos E Lignocelulósicos Para Fotocatálise E Reação De Cuaac Em Fluxo Contínuo

“…23 Esses sistemas transformaram várias metodologias químicas clássicas em sistemas integrados de análise, capazes de fornecer novos conhecimentos sobre a natureza dos processos químicos e a distribuições de transferência de fase e de massa ao longo dos microcanais. 29,30 Na catálise heterogênea, por exemplo, os µRs têm sido utilizados na investigação e caracterização de catalisadores suportados a partir da integração das técnicas de espectroscopia no infravermelho com transformada de Fourier (FTIR, do inglês Fourier-transform infrared spectroscopy) 31,32 , Raman 33,34 , difração de raios X (DRX) 35 e espectroscopia de absorção de raios X (XAS, do inglês X-ray absorption spectroscopy) 36,37 e ressonância magnética nuclear (RMN) 38 .…”

“…Baier e colaboradores (2015), utilizaram uma nova configuração modular composta por um microrreator à base de silício integrado às técnicas de DRX, termografia por infravermelho, RAMAN, e Espectrometria de massas, para análise in situ de catalisadores heterogêneos na oxidação parcial do metano sobre Pt/Al2O3. 35 No mesmo ano, Zhao et al, também desenvolveram uma configuração experimental com integração de microrreatores às técnicas avançadas de análises de composição de raios X, elétrons, ópticas e de fase gasosa para entender as propriedades dos catalisadores suportados durante a hidrogenação do etileno sobre Pt-SiO2. 39 Os µRs também têm sido largamente utilizados como plataformas simples, rápidas e versáteis para a caracterização de novos fotocatalisadores.…”