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The reactions involved in methanol-to-hydrocarbon (MTH) conversion are complex and simultaneous. In this study, the influence of the temperature and weight hourly space velocity (WHSV) was investigated on the MTH kinetic model, which was built on the hydrocarbon pool mechanism using a catalyst of Ca-ZSM-5 (Ca-ZS-5). The existing kinetic model to describe the MTH process is a seven-lump model. The application of any kinetic model for the MTH reaction using the Ca-ZS-5 catalyst has not yet been studied. To obtain high accuracy, new kinetic models were constructed, namely, four- and eight-lump kinetic models. The four-lump model contained oxygenate, olefins, C5+ and paraffin. The eight-lump kinetic model included methanol, dimethyl ether, ethylene, propylene, butylene, C1–C4(sum of CH4, C2H6, C3H8, i-C4H10, and n-C4H10), C5+ (sum of i-C5H12, n-C5H12, and 1-C5H12), and coke. The MTH experiment was performed at 673–773 K and WHSV values of 4.75, 9.5, and 14.25 h–1. The model simulation was carried out by fitting the model equation and experimental data to obtain kinetic parameters using MATLAB software. The results indicated that the four- and eight-lump kinetic models can accurately explain the behavior of the reaction kinetics, especially on the effect of the temperature and WHSV.

Series of nanosized iron- and cobalt-doped ceria–zirconia nanocomposites were prepared using a hydrothermal synthesis technique at 180 °C for 24 h, with the successful novel incorporation of both Co and Fe on ceria–zirconia, for n-hexane catalytic cracking. Effects of dopant ions on the improvement of intrinsic properties of ceria–zirconia nanocomposites were investigated using disparate characterization techniques. The synthesized ceria–zirconia nanocomposites exhibited similar X-ray diffraction (XRD) patterns, indicating full fusion of the metal ions into the ceria–zirconia lattice structure. The synthesized nanocomposite catalysts were tested for n-hexane cracking over 10 h time-on-stream, with no previous study or report for catalytic cracking of hexane via ceria–zirconia nanocomposites. Relatively high ethylene and propylene selectivity (both >62%) was obtained over CZ, FeCoCZa, and FeCoCZb over time-on-stream. Comparatively, the best catalytic activity and stability was exhibited by FeCoCZa with higher n-hexane conversion. Temperature and catalyst weight per feed flow rate (W/F) variations were investigated using the best catalyst (FeCoCZa). Higher conversions were obtained at higher temperature and lower W/Fbut with varied product selectivity and yield, over time-on-stream. In addition, the spent catalysts were successfully regenerated after catalytic testing via calcination at 600 °C for 4 h and reused for two additional cycles.

For the first time, a sequential fabrication step involving mechanochemistry, recrystallization, and dealumination was developed to convert low-cost natural zeolites to mordenite (MOR) nanoparticles. Natural zeolites are mostly found having poor textural properties and a high aluminum content, which are not suitable for most industrial catalytic reactions. The parent natural zeolites within the size of 1–10 μm were treated by ball milling to obtain nanosized particles with size in the range of 20–160 nm. The nitrogen physisorption study revealed that the external surface area and intercrystalline mesopore volume of the milled nanoparticles increased by 4- and 7-fold, respectively. Recrystallization by hydrothermal treatment in basic silicate solution was applied to recover the MOR crystallinity at 170 °C for 6 h. The recrystallized MOR samples were further subjected to acid dealumination treatment over different periods. The H-MOR samples were evaluated in a fixed-bed reactor for n-butane isomerization. The isobutane selectivity increased from 11 to 28% when the parent microparticle was substituted by the recrystallized nanoparticles. Moreover, the catalyst stability improved over the recrystallized nanoparticles. The dealuminated–recrystallized nanoparticle exhibited the highest selectivity of ca. 58% to isobutane and less deactivation rate as a result of low acid site density and small nanoparticle size.