Microreactor high-pressure

This study presents kinetic data obtained with a microreactor set-up both at atmospheric pressure and at high pressures up to 50 bar as a function of temperature and of the partial pressures from which power-law expressions and apparent activation energies are derived. An additional microreactor set-up equipped with a calibrated mass spectrometer was used for the isotopic exchange reaction (DER) N2 + N2 = 2 N2 and the transient kinetic experiments. The transient experiments comprised the temperature-programmed desorption (TPD) of N2 and H2. Furthermore, the interaction of N2 with Ru surfaces was monitored by means of temperature-programmed adsorption (TPA) using a dilute mixture of N2 in He. The kinetic data set is intended to serve as basis for a detailed microkinetic analysis of NH3 synthesis kinetics [10] following the concepts by Dumesic et al. [11]. 

F. Benito-Lopez, W. Verboom, M. Kakuta, et al.. Optical fiber-based on-line UV/Vis spectroscopic monitoring of chemical reaction kinetics under high pressure in a capillary microreactor, Chem. Commun., 2857-2859 (2005). 

Figure 2. Schematic of valve manifold assembly, microreactor, radiant heater, and high pressure assembly depicting vacuum and high pressure operation.

Apparatus. The experiments were conducted in a high-pressure microreactor capable of operating up to 3000 psig. The reactor, enclosed by a three-zone heater, had an isothermal reaction zone holding up to 10... 

Utilizing a commercially available microreactor, fabricated from FOR-TURAN glass, Fukuyama et al. (2004) evaluated a series of [2 + 2] cycloadditions as a means of reducing the reaction times conventionally associated with the synthetic transformation (Table 27). Using a high-pressure mercury lamp (300 W), the reaction of cyclohex-2-eneone 179 with vinyl acetate 168 (Scheme 51), to afford the cycloadduct 180, was used to compare photochemical efficiency within the microreactor [1,000 pm (wide) x 500 pm (deep)] and a conventional batch reactor (10 ml). 

A cartridge heater is inserted in the cover plate of the packed-bed reactor [277]. The base plate provides conduits to the microreactor. The outlets are standard high-pressure fittings. Thermocouples are inserted into the slurry feed channels. 

Carbon deposition rates were measured in a microreactor connected to a Sartorius 4436 high pressure microbalance [11]. The catalyst (17-70 mg) was placed on quartz wool in a perforated quartz basket in a stainless steel reactor lined with an alumina tube (i.d. = 15 mm) and hung from one arm of the microbalance by a quartz fiber. Water was fed using a Lewa M3 pump. A flow of inert gas was always maintained through the microbalance. The composition of the product gas could be determined by on-line gas chromatography. 

Catalytic activity was studied in laboratory and bench-scale reactor systems. Laboratory catalytic tests (n-hexane conversion) were carried out in a through-flow reactor under the following conditions T=200-450 °C LHSV=7 h. Bench-scale tests were run in a continuous -flow high-pressure microreactor unit, using diesel oil as a feedstock. Catalysts were reduced and then sulfided at 330 °C for 5 h. The process was studied at T=300-330 °C, LHSV=3 h p=3.5 MPa and H2 CH=500 Nm /m. The criterion for catalyst activity assessment was the freezing point (-20 °C) the measurements were done for the stabilized products. 

Several recent reviews have discussed the fundaments and applications of PI concepts. Doble [16] has discussed the concept of a green reactor, for example, how process intensification could be achieved by microreactor technology using very high forces, ultra-high pressures, electrical fields, ultrasonics, surfactant-based separations, shorter diffusion and conduction pathways, flow field and fluid microstmcture interactions, and/or size-dependent phenomena. 

The main drawback of randomly packed microreactors is the high pressure drop. In multitubular fixed-bed microreactors, all channels must be packed identically, or supplementary flow resistances must be... 

F. Trachsel, C. Hutter, P.R. von Rohr, Transparent silicon/glass microreactor for high-pressure and high-temperature reactions, Chem. Eng. J. 135 (2008) S309. 

For the flow conditions given in Example 4-4 in a l(K)0-f( length of Ij-in. schedule 40 pipe (oip = 0.0118). the pressure drop is less than 10%, However, for high volumetric flow rates through microreactors, the pressure drop may be significant. 

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