Reactor silicon

Stainless steel is the material of choice for process chemistry. Consequently, stainless steel microreactors have been developed that include complete reactor process plants and modular systems. Reactor configurations have been tailored from a set of micromixers, heat exchangers, and tube reactors. The dimensions of these reactor systems are generally larger than those of glass and silicon reactors. These meso-scale reactors are primarily of interest for pilot-plant and fine-chemical applications, but are rather large for synthetic laboratories interested in reaction screening. The commercially available CYTOS Lab system (CPC 2007), offers reactor sizes with an internal volume of 1.1 ml and 0.1 ml, and modular microreactor systems (internal reactor volumes 0.5 ml to... 

Researchers at Lehigh University are developing a methanol reforming silicon reactor with a palladium membrane for a hydrogen purification system built using semiconductor fabrication techniques. The device is designed to produce hydrogen for fuel cells for portable electronic devices, such as laptop computers and cell phones. 

Later, Pattekar and Kothare [21] presented a silicon reactor fabricated by deep reactive ion etching (DRIE). It carried seven parallel micro channels of 400 pm depth and 1 000 pm width filled with commercial Cu/ZnO catalyst particles (from Siid-Chemie) trapped by a 20 pm filter, which also was made by DRIE, in the reactor. The reactor was covered by a Pyrex wafer applying anodic bonding. Details of the reactor are shown in Figure 2.3. 

Figure 2.54 Single-channel silicon reactor with pre-mixer and outlet cooler [86]...

Besser et al. [86] studied the reaction in a silicon reactor fabricated by applying MEMS technology, namely photolithography and DRIE by inductively coupled plasma. Each reactor incorporated dual gas inlets, a pre-mixer, a single reaction channel and an outlet zone where the product flow was cooled (see Figure 2.54). The single channel was 500 pm wide, 470 pm deep and 45 mm long. 

The first uses of microtechnology for screening applications were presented recently. For instance, Watts and Haswell [2] presented first work on microfluidic combinatorial organic chemistry. Most of the examples described apply to glass, polymer or silicon reactors, which restricts their usage to low-pressure operation similar to pharmaceutical applications. They concluded that micro reactors could be a tool for rapid reaction development and process optimization. 

The typical epi silicon reactor operates in the diffusion-controlled regime at high rates of deposition. The behavior of such a reactor is governed by the fluid dynamics of multicomponent gases. The gas phase reactions discussed in Chapter 1 are generally neglected. 

Figure 13 Vertical pancake epi silicon reactor chamber—Gemini Research.

Boro-Silicone [Reactor], TM for fire- and heat-resistant field-castable elastomer with high hydrogen content. A solid material with resiliency to... 

Jensen and coworkers studied phosgene synthesis using a micropacked-bed reactor [7]. A silicon reactor consisting of a 20 mm long, 625 (im wide and 300 pm deep reaction channel (volume 3.75 mL) was employed (Figure 11.2). In order to avoid corrosion by chlorine, the microchannels were coated with a thin sflicon dioidde film (5000.. A fixed bed of activated carbon catalyst (1.3 mg, 53-73 pm) supported on alumina particles ( 3mg, 53-71 pm) was placed inside the microchannel. Chlorine and CO were mixed and fed into the microchannel network. The exit stream could be analyzed on-line using a mass spectrometer. 

A prototype for a methanol reforming silicon reactor was designed at Lehigh University [11,12,31]. Their microreaction system, made of silicon wafers, consisted of four main components a mixer/vaporizer of methanol and water, a catalytic steam reformer with a copper catalyst, the combined water gas shift reactor-membrane (as mentioned before) and integrated resistive heaters, sensors and control electronics. The reformer was tested with a stainless-steel housing. The authors reported a conversion of 90% for methanol, which corresponds to a power output of 15 W. 

Ouyang et al. [147] studied the preferential oxidation of carbon monoxide in silicon reactors of the smallest scale fabricated by photolithography and deep reactive ion etching. The reactors had two gas inlets for reformate and air, a premixer, a single reaction channel, and an outlet zone where the product flow was cooled. The chaimels were sealed by anodic bonding with a Pyrex glass plate. Full conversion of carbon monoxide was achieved between 170 and 300° C reaction temperature. 

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