Nonoxidative methane activation, coupling, and conversion to ethane, ethylene, and hydrogen over Fe/HZSM‐5, Mo/HZSM‐5, and Fe–Mo/HZSM‐5 catalysts in packed bed reactor

Abstract

Summary A high abundance of methane and its relatively low price make it an attractive raw feedstock for the production of ethylene, which is in the consumer demand in recent years. Direct catalytic nonoxidative conversion is interesting, because it could be utilized on natural gas well sites. Monometallic and bimetallic Fe and Mo catalysts were prepared for the purpose of the coupling to ethane and ethene. Three supported materials were synthesized with the following loading of metal: 2.5‐wt% Fe, 5.0‐wt% Fe, and 2.5‐wt% Mo on HZSM‐5. Process' chemical reactions were also catalyzed with a constant 2.5‐wt% Mo/HZSM‐5, which had different amounts of Fe, namely, 0.5, 1.0, and 2.5 wt%. Fourier transform infrared (FTIR), N2 adsorption/desorption, NH3 temperature‐programmed desorption (TPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffraction (XRD) were applied for characterization. Coke, accumulated on spent solids, was determined by thermogravimetric analysis (TGA). Activity was evaluated in quartz‐packed bed reactor. All surfaces suffered from deactivation due to carbon formation. The addition of Fe to Mo increased CH4 reacted. The highest selectivity for alkenes was achieved over 1.0‐wt% Fe to 2.5‐wt% Mo/HZSM‐5. At the peak of performance, the C‐based reactivity was 52% for olefins and 2% for alkanes. Stability was accomplished over 2.5‐wt% Fe/HZSM‐5, where the rate of C2 synthesis was comparatively stable for 20 hours of the time on stream. The selective C‐basis yield for C2H4 and C2H6 was 36% and 23%, respectively. The lowest measured quantity of (carbonaceous) by‐products was deposited on 2.5‐wt% Fe/HZSM‐5 after 26 hours. Propylene was detected very limitedly.

Fibrous spherical Ni‐M/ZSM‐5 (M: Mg, Ca, Ta, Ga) catalysts for methane dry reforming: The interplay between surface acidity‐basicity and coking resistance

“…Figure shows the XRD patterns of commercial and fibrous spherical ZSM‐5 (FZSM‐5)‐supported nickel catalysts. A detailed examination reveals diffractograms within peak range of 2θ = 7‐10° and 22‐25°, which is allotted to ZSM‐5 phase (JCPDS file number 37‐359) . In addition, formation of NiO cubic phase around 2θ = 37.28, 43.2 and 62.5, which corresponds to the (111), (200) and (220) reflections were observed for all supported Ni catalysts .…”

“…Synthesis gas (syngas), a versatile feedstock, has been widely used in the chemical industry as a starting material for the production of liquid energy carriers and high value‐added chemicals . One of the environmentally benign pathways for syngas production is dry reforming of methane (DRM): CH 4 + CO 2 ⇌2CO + 2H 2 , ΔH o 298 K = 260.5 kJ mol −1 .…”

Recent advances in heterogeneous catalysis for the nonoxidative conversion of methane

“…The addition of metal promoters is also beneficial for reducing the formation of coke in zeolite channels. For instance, in the work performed by Bajec et al , 52 the addition of Fe to Mo/HZSM-5 catalysts reduces the amount of coke formation, which results in a better stability for the coupling of methane to ethane/ethylene synthesis. The effect of the addition of Fe, Rh, and K on MDA over Mo/HZSM-5 was studied by Ramasubramanian et al , 53 in which the K-promoted catalyst was found to have a better selectivity for benzene (∼50%) after 255 min of reaction ( Fig.…”

Performance study of Ni, Co, and Mo catalysts supported on γ ‐Al 2 O 3 and HZSM5 in HDS reactions of mixed naphtha

“…Also, HZSM5 has been used for various processes in other research studies. [38][39][40] Consequently, there will be enough reasons and attractiveness to study these series of catalysts. Recently, mesoporous materials have been considered as catalyst support for different applications.…”

“…Sharifi et al 37 have investigated the effect of HZSM5 (zeolite support) with different SiO 2 /Al 2 O 3 ratios for HDS and aromatization catalytic processes parallel to each other, and their results showed that a significant increase in the Research Octane Number (RON) from 51.9 to 93 for naphtha feed stock largely covers the medium HDS performance of prepared catalysts. Also, HZSM5 has been used for various processes in other research studies 38‐40 . Consequently, there will be enough reasons and attractiveness to study these series of catalysts.…”