Concentration-Dependent Kinetic Model for Catalyst Deactivation in the MTG Process

Abstract

From experimental results obtained in a wide range of operating conditions (temperature and contact time) in an isothermal fixed-bed integral reactor, the usefulness of the model of Schipper and Krambeck (Chem. Eng. Sci. 1986, 41, 1013−1019) for simulating the operation has been proven in the 300−375 °C range. The validity of a deactivation kinetic model dependent on the composition of the three lumps for the MTG process (oxygenates, light olefins, and the rest of the products) has been proven, for a wide interval of compositions of the lumps. These compositions correspond to different states of catalyst deactivation. The use of this model in the simulation of the integral reactor avoids noticeable errors inherent to the nonconsideration of the effect of composition on the deactivation.

Olefin production by cofeeding methanol and n‐butane: Kinetic modeling considering the deactivation of HZSM‐5 zeolite

“…Equations dependent on the concentration of reaction components have been proposed in the literature by considering that oxygenates are the main coke precursors, although this formation is also favored by the concentration of C 2 AC 4 olefins and C 5þ lump. 15,43,44 Coke formation from oxygenates is explained through the ''hydrocarbon pool'' mechanism, 26,27,45,46 and coke formation mechanism on HZSM-5 zeolites from olefins and aromatics, which are well-established in the literature. 35,47 The results of coke content deposited on the catalyst for different values of space time at 450 and 500 C (Table 3) reveal that coke deposition is favored by higher-concentrations of oxygenates in the reaction medium (corresponding to a lower-space time).…”

A detailed kinetic model for biogas steam reforming on Ni and catalyst deactivation due to sulfur poisoning

“…There are several review articles outlining various aspects of catalyst poisoning [9,10], however, models that deal with catalyst poisoning are really scarce in literature. The general practice in modeling catalyst poisoning is to express the activity, i.e the ratio of true rate to the initial rate, as a function of time and poison concentration [11,12,13,14]. This work appears to be the first attempt to model sulfur poisoning on Ni catalyst using a detailed kinetic model.…”

Reactivation of the HZSM‐5 zeolite‐based catalyst used in the MTG process

“…The theory that the acidic site deterioration of the catalyst affects each of the individual steps of the kinetic scheme equally is based on the verification made in a previous work (Gayubo et al, 1996a). There it was shown that the same acidic sites take part in the individual steps by which light olefins form and on their transformation into hydrocarbons of gasoline in the boiling point range.…”

“…The feed-reaction-analysis system is controlled by a computer routine. Calculation of the weight fraction of the lumps of oxygenates (methanol and dimethyl ether), of light olefins (ethylene, propyiene, and butenes), and of the rest of the products is carried out using a program in FORTRAN, which is based on the composition of each individual product obtained in the chromatographic runs (Benito et al, 1996a).…”

“…A kinetic equation for deactivation of the separate functions (Sztpe and Levenspiel, 19711, depending on the concentration of the three sections of the reaction scheme, which are possible coke precursors, has been proven (Benito et al, 1996a;Aguayo et al, 1997), considering only deactivation by coke deposition:…”