Effect of Cofeeding Butane with Methanol on the Deactivation by Coke of a HZSM-5 Zeolite Catalyst

Abstract

The deactivation by coke of a HZSM-5 zeolite catalyst has been studied in the transformation of methanol into hydrocarbons by cofeeding butane (n-butane). This reaction is of interest as an energy-neutral integrated process that enhances the activity in the cracking reaction and upgrades the paraffins formed as byproducts. The process was carried out in a fixed-bed reactor under the following conditions: temperature, 550 °C; pressure, 1 bar; space time, 2.4 and 4.8 (g of catalyst) h (mol of CH 2 ) À1 ; time on stream, 5 h; methanol/butane molar ratio, up to 16/1. The coke was characterized using several analytical techniques (TGÀTPO, FTIR, Raman, and NMR spectroscopies), and the effects of cofeeding butane on the coke composition and structure were determined. The results in terms of coke content and composition, are explained in terms of the different pathways of methanol and butane transformation.

Kinetic and Deactivation Differences Among Methanol, Dimethyl Ether and Chloromethane as Stock for Hydrocarbons

“…We have solved this issue comparing experimental results at different conversion values and with molecular modelling simulations. One key difference among the process is the change of the reaction medium composition, which affects the product distribution and deactivation . At similar level of conversions, DTH and MTH reactions have similar product distribution.…”

Coke formation and deactivation during catalytic reforming of biomass and waste pyrolysis products: A review

“…Nevertheless, in base transition metal catalysts (Ni, Fe, Co), metal oxidation during TPO is considerable and leads to a mass gain, which masks the mass loss by combustion and thus the coke content cannot be directly determined. In this regard, an interesting solution consists on coupling TG-TPO with the analysis of the combustion exhausts with mass spectrometry (MS) (TG-MS/TPO) [71,111,[138][139][140][141][142][143]215,218,219,273,274], and determining the coke content from the quantified CO2 signal in MS. This procedure involves O2 in excess in the reaction medium, in order to assure complete combustion and negligible CO concentration.…”

Nature and Location of Carbonaceous Species in a Composite HZSM-5 Zeolite Catalyst during the Conversion of Dimethyl Ether into Light Olefins

“…From the industrial perspective, C5+ aliphatics and some paraffins, as butane, could be recirculated for boosting olefin production and controlling coke deactivation [32]. Figure 1b shows the values of selectivity of light olefins at different temperatures for time on stream values of 0 and 18 h. As the temperature is increased, the selectivity of olefins decreases due to the faster secondary reactions of those: (i) oligomerization-cracking, leading to C5+ aliphatics; (ii) hydrogen transfer, leading to paraffins and aromatics; and (iii) condensation, leading to coke.…”