Selective Isomerization of n-Butane over Mordenite Nanoparticles Fabricated by a Sequential Ball Milling–Recrystallization–Dealumination Route

Abstract

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.

Isomerization of n-Butane over Cost-Effective Mordenite Catalysts Fabricated via Recrystallization of Natural Zeolites

“…This enhanced the access of n -butane into the high strong acid sites in the side pocket of 8-MR channels. This finding was in agreement with literature reports that the acid treatment created the access to the new micropore channels in the side pocket. , Niwa et al studied the acid sites in the 8-MR and found they were stronger than those in the 12-MR. Hence, the high selectivity to isobutane over the H-P-H is most likely contributed through the monomolecular pathway on the strong acid sites.…”

Development of New Kinetic Models for Methanol to Hydrocarbons over a Ca-ZSM-5 Catalyst

“…The important factors influencing the product distribution on the MTH process were process reaction conditions (temperature, WHSV, and pressure), ,− acidity of the catalyst, ,− and morphology and structure of the ZS-5 catalyst. ,,,− In this experiment, the effect of the temperature, calcium metal impregnation over the ZS-5 catalyst, and WHSV was evaluated on the product distribution for the MTH reaction.…”

“…The results showed that a modified ZSM-22 catalyst with iron could enhance the catalyst lifetime and selectivity for 3 h and 54%, respectively. In addition, Kurniawan et al 12 studied the modified natural zeolite for increasing the isobutene selectivity from n-butane. They found that ball milling of natural mordenite followed by hydrothermal recrystallization could recover the crystallinity of natural zeolite nanoparticles and, as a result, increase the isobutene selectivity.…”

Alkane isomerization over sulfated zirconia solid acid system

“…From this point, the zeolite catalysts are thermodynamically less favorable in n ‐alkane isomerization despite that there are many attempts made on them. The zeolite catalysts must be operated at a higher temperature, typically 200°C to 300°C because of their weaker acidity compared with the Cl‐Al 2 O 3 and SZ catalysts . In conclusion, the SZ‐based catalysts not only have a satisfied catalytic performance in n ‐alkane isomerization compared with the Pt/Cl‐Al 2 O 3 catalysts but also have no problem with the loss of active components.…”