Kinetic modelling of methanol synthesis over commercial catalysts: A critical assessment

Kinetic modelling of methanol synthesis over commercial catalysts is of high importance for reactor and process design. Literature kinetic models were implemented and systematically discussed against a newly developed kinetic model based on published kinetic data. Deviations in the sensitivities of the kinetic models were explained by means of the experimentally covered parameter range. The simulation results proved that an extrapolation of the working range of the kinetic models can lead towards significant simulation errors especially with regard to pressure, stoichiometric number and CO/CO$_{2}$-ratio considerably limiting the applicability of kinetic models frequently applied in scientific literature. Therefore, the validated data range for kinetic models should be considered when detailed reactor simulations are carried out. With regard to Power-to-Methanol processes special attention should be drawn towards the rate limiting effect of water at high CO$_{2}$ contents in the syngas. Moreover, it was shown that kinetic models based on data measured over outdated catalysts show significantly lower activity than those derived from state-of-the-art catalysts and should therefore be applied with caution for reactor and process simulations. The plausible behavior of the herein proposed kinetic model was demonstrated by a systematic comparison towards established kinetic approaches within both, an ideal kinetic reactor and an industrial steam cooled tubular reactor. Relative to the state-of-the-art kinetic models it was proven that the herein proposed kinetic model can be applied over the complete industrially relevant working range for methanol synthesis

Factors affecting anaerobic digester adoption in the West

Current climate policy focuses disproportionately on carbon dioxide emissions but recent developments have begun to recognize the important role of other gases, including methane. As a result, anaerobic digesters (ADs) on dairy farms present an opportunity to reduce greenhouse gas emissions. We quantify the social and private costs and benefits of ADs that have been adopted in California and find that despite high initial costs, large reductions in GHG emissions bring significant social benefits and represent good social investments given a $36 per-ton carbon price. Subsidies that lower the initial private investment cost can help align socially and privately optimal adoption decisions

KYHP3O10 : Rietveld refinement using x-ray powder diffraction data and Raman study of the conductivity phase transition

Potassium yttrium hydrogen triphosphate (KYHP3O10) crystallises in the triclinic system P1̄ at room temperature with the following parameters: a=6.8522(2), b=7.6254(2), View the MathML sourceα=106.658(1), β=106.435(2) and γ=82.344(2)°; Z=2. This structure has been refined from X-raypowderdiffractiondata using the Rietveld method, with the isostructural compounds KSmHP3O10 and NH4BiHP3O10 as the starting model. Refinement of 70 parameters by the Rietveld method, using 2447 reflections, led to cRwp=0.138, cRp=0.104 and RB=0.041. This compound is a chain-based structure. The K+ and Y3+ cations are intercalated between chains, formed of (HP3O104−) groups linked by OH⋯O hydrogen bonding along the c-axis. The yttrium atoms are in an eight-fold coordination and also build infinite chains of edge-sharing YO8 polyhedra running parallel to the a-axis. The potassium cations are coordinated by 10 oxygen atoms and build chains of KO10 polyhedra running parallel to the b-axis. A calorimetric study of the title compound shows one endothermal peak, which is detected at 519 K. Samples were examined by impedance and Raman spectroscopy techniques. The Raman spectra of KYHP3O10, recorded at different temperatures in the frequency range 50-1250 cm−1 show the presence of a transition, which is characterised by an unusual high conductivity caused by breaking of the hydrogen bridges and suggests a great dynamic disorder of protons. This permits H+ ions at high temperature to contribute with the potassium cations to the ionic conductivity of the product

PFC herd replacement comparisons (version 1) - worksheet

September 2017.In the production cycle of a cow-calf enterprise, the producer will face the decision of replacing their older cows. The producer deciding to replace older cows with heifers has the following options: raise their own replacement heifers, buy open heifers and breed them, or buy bred heifers. The options vary in price, timing, and expense. The tool created is a cost-effective analysis between the three options: buying bred, buying open, or raising their own heifers

Ozonkiller vermeiden Verbraucherratgeber der FCKW-Stop Initiative

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman