Experimental and kinetic modeling of Fischer-Tropsch synthesis over nano structure catalyst of Co-Ru/carbon nanotube

摘要

In this work, the nanostructure catalyst of Co-Ru/CNTs is prepared by chemical reduction technique. Then, a set of catalytic experiments are designed and conducted for the Fischer-Tropsch synthesis (FTS) using the synthesized catalyst in a fixed bed reactor. The physical and chemical properties of the support and the synthesized catalyst were determined using the BET, XRD, H-2-TPR, TEM, and H-2-chemisorption characterization techniques. Based on the alkyl mechanism and using the Langmuir-Hinshelwood-Hougen-Watson (LHHW) isotherm, a kinetic model is developed for FTS. In most of the previous kinetic models, the primary reactions have merely been used, but in the current derivation of the developed kinetic model, the secondary reactions (adsorption, hydrogenation and chain-growth) and re-adsorption of primary olefins at the secondary active sites are considered. The present comprehensive kinetic model is applied for the product distribution such that the rate equations parameters are acquired via optimization. To estimate the kinetic model parameters, FTS was accomplished via a series of tests under the operating conditions as pressure (P): 10-20bar, temperature (T): 483-513K, gas hourly space velocity (GHSV): 1400-2400h(-1) and the H-2/CO ratio of 1-2. The rationality and significance of the suggested model were checked through the statistical and correlation tests. The obtained results indicated that the outcomes of the current kinetic model were in good agreement with the experimental data. Using the present kinetic model, the average absolute deviations (AAD%) for the prediction of methane, ethylene and heavier hydrocarbons (C-5(+)) formation rates are obtained as 7.06%, 11.57% and 14.74%.