Methanol synthesis was carried out at 25 bar in slit formed by two parallel plates 5 mm apart. Upper plate was covered by catalyst layer and heated up to 250C, whereas lower one was kept at about 30C. Reaction stream in laminar flow consisted of H2, CO2, and CO in concentration range usually encountered in industrial processes. Catalyst layer was prepared by spraying CuO/ZnO/Al2O3/V2O3 slurry on SS-plate. Continuous removal of methanol and water by condensation on the cool surface shifted equilibrium toward products formation. At isothermal conditions with no temperature gradient in slit, total carbon conversion approached the thermodynamic equilibrium when residence time was long enough. Experiments with high temperature difference showed total carbon conversion much larger compared to the thermodynamic one calculated at plate-catalyst temperature. Three-dimensional model predicted total carbon conversion for both isothermal and high temperature gradient operation reasonably well.
COBISS.SI-ID: 5408538
Methanol decomposition on Pt/CeO2/ZrO2 catalyst is studied inside a packed bed microreactor in the temperature range of 300 -380 deg. C. The microreactor is fabricated using low-temperature co-fired ceramic (LTCC) technology, which is well suited for the production of relatively complex threedimensional structures. It is packed with 2 wt% PteCeO2 catalyst, which is deposited onto ZrO2 spherical particles. A 1D mathematical model, which incorporates diffusion, convection and mass transfer through the boundary layer to the catalyst particles, as well as a 3D computational fluid dynamics model,are developed to describe the methanol decomposition process inside the packed bed. The microreactor exhibits reliable operation and no catalyst deactivation was observed during three months of experimentation. A comparison between the 1D mathematical model and the 3D model, considering the full 3D geometry of the microreactor is made and the differences between the models are identified and evaluated.
COBISS.SI-ID: 5432602
A spraying method for coating stainless steel surfaces with a commercial methanol synthesis catalyst was studied for the purpose of making a thin, active, and durable plate catalyst. The catalyst slurry was composed of CuO/ZnO/Al2O3/V2O3 powder dispersed in 2-propanol and was sprayed on a curved stainless steel surface. The coating was found to exhibit good adhesion to the metal surface and to provide a considerable increase in surface area relative to the geometrical area of the metal support surface (up to a factor of 11000). The effects of key method parameters, namely, the size of the catalyst particles in the suspension and the coating thickness, on the efficiency of coating and the morphology and durability of the coating were briefly investigated. The intrinsic kinetics of carbon dioxide and carbon monoxide hydrogenation, as well as the WGS reaction, on the prepared plate catalyst were evaluated and compared to literature data. The reactions were carried out in a continuous stirred-tank reactor (CSTR) system appropriately assembled with a curved plate catalyst in the absence of mass-transfer limitations.
COBISS.SI-ID: 4899866
Intrinsic kinetics study of steam methane reforming (SMR) was performed on two different systemscommercial Ni-based pellet catalyst and Pt/Ni/Al2O3 structured plate catalyst. Experiments were carried out in the absence of external mass transfer resistance, and temperature 500−575 °C, pressure 2.5−7.5 bar, and H2O/CH4 reactant ratio range of 3−5 mol/mol. Reactors operated in the integral mode, and it was shown that both systems could be described by the same kinetics, based on Langmuir−Hinshelwood mechanism. In the case of plate catalyst, the regeneration treatment after deactivation led to platinum particle redispersion, which further influenced the values of the pre-exponential factors, whereas the activation energy values remained unchanged. Comparison of the two catalyst systems was made based on the active metal content, and it was shown that the catalytic activity of the Pt/Ni/Al2O3 plate catalyst after the second regeneration treatment was 8 times of that observed for the Ni-based pellet catalyst.
COBISS.SI-ID: 5299482
The sorption reaction CaO−CO2 was examined in a countercurrent gas−solid trickle flow reactor with regularly stacked packing at T = 500−600 oC, pCO2 = 40−50 kPa, solid phase fluxes, S = 0.3−0.5 kg m−2s−1, and CaO particles of 500−710 μm in size. Sorption kinetics was evaluated by thermogravimetric (TG) technique. The random pore model was used for the description of the carbonization reaction. Hydrodynamic characteristics of gas−solid trickle flow were estimated at room temperature and ambient pressure. Plug flow model of both gas and solid phase, with the parameters obtained from TG and hydrodynamics experiments, satisfactorily described the sorption process in countercurrent gas−solid trickle flow reactor.
COBISS.SI-ID: 5660186