Thin-film micro reactor

Reactor 5 [R 5] Single-/Tri-channel Thin-film Micro Reactor... 

Figure 5.7 Schematic of the single-channel thin-film micro reactor [15],...

A coolant channel is guided through the metal block in a serpentine fashion [15], Hence reactant and coolant flows are orthogonal. A thermocouple measures the temperature at the product outlet of the single-channel thin-film micro reactor. 

Reactor type Single-channel thin-film micro reactor Bottom plate (metal block) material Nickel (or copper)... 

Reactor type Three-channel thin-film micro reactor Micro device outer 96 x 52 x 12 mm dimensions... 

GL 1[ [R 1[[P la[ By autofocus laser imaging, the average position of the liquid surface in all micro channels of a reaction plate of a falling film micro reactor was determined [3]. It was found that very thin films of the order of 20-25 pm were formed for total volume flows of 20-80 ml h The thickness of the films in the various channels differed, but by no more than 30% on average. At high flows, e.g. > 180 ml hr, flooding of the channels occurs. 

P 12] A falling film micro reactor was applied for generating thin liquid films [6]. A reaction plate with 32 micro channels of channel width, depth and length of 600 pm, 300 pm and 66 mm, respectively, was used. Reaction plates made of pure nickel and iron were employed. The micro device was equipped with a quartz window transparent for the wavelength desired. A 1000 W xenon lamp was located in front of the window. The spectrum provided ranges from 190 to 2500 nm the maximum intensity of the lamp is given at about 800 nm. 

GL 16] ]R 12] ]P 15] Using a simple thin-film model for mass transfer, values for the overall mass transfer coefficient were determined for both micro-channel processing and laboratory trickle-bed reactors [11]. The value for micro-reactor processing (fCL = 5-15 s ) exceeds the performance of the laboratory tool Ki a = 0.01-0.08 s ) [11, 12], However, more energy has to be spent for that purpose (see the next section). 

Additionally, thin-film layers of the catalyst may be deposited on to the surface of the micro channels by sputtering [73] or CVD [63], In the latter case, aluminum isopropoxide, Al[(CH3)2CHO]3, was used as alumina precursor, which was passed through a ready-stacked reactor at 300 °C for 1 h in a flow containing nitrogen and oxygen in addition. The flow direction was subsequently changed and the procedure repeated. 

E. V. Rebrov, A. Berenguer-Murcia, B. F. G. Johnson, J. C. Schouten, Gold supported on mesoporous titania thin films for application in micro structured reactors in low-temperature water-gas shift reaction, Catal. Today 138 (2008) 210-215. 

L h for the falling film microreactor. The authors explain the increase in selectivity with the fact that in the micro reactor the concentration of chlorine radicals can be kept lower due to its large surface-to-volume ratio. In the microreactor, the entire fluid film can be penetrated by the inddent light, in contrast to the batch reactor, where only a thin film of the fluid is irradiated in the vicinity of the light... 

Figure 8.16 shows a methanol/water vaporiser, followed by a catalytic steam reformer operating at about 250°C, in which the catalyst is a thin film of Cu/ZnO coated onto the silica reactor, and finally a membrane shift reactor consisting of a palladium diffusion layer mounted on top of a perforated copper-based shift catalyst. Built onto the chip are integrated resistive heaters for getting the reformer and vaporiser up to temperature, together with micro-scale sensors and control electronics. Whilst such systems are a long... 

Fig. 6.6. Potassium-promoted iron oxide for the dehydrogenation of ethylbenzene to styrene. (A) A SEM image of the technical catalyst with its internal interface. (B) Production rate of styrene over 1 cm of model catalyst. (C) Micro-reactor for testing single-crystalline thin-film catalysts under ambient conditions with no background activity from the reactor itself (D) STM image of the K2pe22034 active phase.

Since no synthetic chemistiy infrastructure was available at the Department (or, indeed, the Institute) before 2008, polyciystalline samples of catalysts had to be obtained from external, often industrial, partners. In order to produce model systems in house, researchers in the Department of Inorganic Chemistry developed a suite of instruments allowing the synthesis of metal oxides by physical vapor deposition of elements and by annealing procedures at ambient pressure. They chose the dehydrogenation of ethylbenzene to styrene on iron oxides as the subject of their first major study. Figure 6.6 summarizes the main results. The technical catalyst (A) is a complex convolution of phases, with the active sites located at the solid-solid interface. It was possible to synthesize well-ordered thin films (D) of the relevant ternary potassium iron oxide and to determine their chemical structure and reactivity. In parallel. Department members developed a micro-reactor device (B) allowing them to measure kinetic data (C) on such thin films. In this way, they were able to obtain experimental data needed for kinetic modeling under well-defined reaction conditions, which they could use to prove that the model reaction occurs in the same way as the reaction in the real-life system. Thin oxide... 

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