Abdullah Aitani's research while affiliated with King Fahd University of Petroleum and Minerals and other places

In this study, we introduce a hierarchical core–shell ZSM-5@SiO2 zeolite catalyst to explore its effects on the catalytic cracking of heavy atmospheric gas oil into olefins and how the water/oil ratio influences the process. The modified core–shell zeolite and ZSM-5 catalysts were characterized, employing a suite of techniques, including BET, SEM, HR-TEM, XRD, and NH3-TPD, both before and after a steaming treatment. The parent ZSM-5 zeolite, encapsulated by a 24 nm thin amorphous-SiO2 layer, undergoes significant physical changes upon steaming, which induces the formation of additional mesopores and decreases the catalyst acidity. In the absence of steam cofeeding, the catalytic cracking favored bimolecular reactions, yielding limited olefin selectivity. However, introducing steam into the process significantly enhanced the performance, increasing olefin selectivity dramatically from 23.8 to 69%. Furthermore, the propylene/ethylene ratio was favorably stirred from 0.7 to 1.4 with an increasing water/oil ratio, highlighting the critical role of steam in shifting the reaction toward monomolecular pathways and promoting the production of lighter olefins. This study emphasizes the synergistic effects of mesoporosity enable large-molecule diffusion, moderate acidity, and steam cofeeding in optimizing the catalytic cracking process for higher olefin yield.

Ethane, one of the key components of shale gas, is a valuable feedstock for the production of syngas (CO + H2) via the Csingle bondC bond cleavage during dry reforming of ethane (DRE) reaction. Selective catalysts are needed to direct this reaction pathway against the competing Csingle bondH bond cleavage for ethylene formation. In this study, Fe, V and Rh oxides supported on TiO2 catalysts were prepared by impregnation method. The catalysts were tested for DRE with the main target of enhancing selectivity to syngas (CO and H2) and reducing byproducts (methane and ethylene) formation. The catalysts were characterized using X-ray diffraction, scanning electron microscopy, NH3/CO2 temperature programmed desorption and H2-temperature programmed reduction. Temperature programmed oxidation was utilized to characterize the coke contents of the spent catalysts. The catalysts were evaluated for DRE reaction in a fixed-bed reactor at the temperature range from 500 °C to 650 °C and CO2/ethane ratio from 2.0 to 10.0 (mol/mol). It was found that ethane conversion over the three catalysts increased in the order Rh/TiO2 > Fe/TiO2 > V/TiO2. Rh/TiO2 catalyst exhibited > 99 % ethane conversion, 36 % and 61 % yields of H2 and CO, respectively, at 650 °C and CO2/ethane ratio of 5.0. The high conversion of ethane was mainly attributed to the enhanced dispersion of Rh oxides on the TiO2 support coupled with the balanced surface acidic and basic sites. The Rh catalyst facilitated Csingle bondC bond dissociation of ethane thereby forming methyl intermediates which then reacted with adsorbed CO2, thereby enhancing syngas production during DRE reaction.

The prediction of the yields of light olefins in the direct conversion of crude oil to chemicals requires the development of a robust model that represents the crude-to-chemical conversion processes. This study utilizes artificial intelligence (AI) and machine learning algorithms to develop single and ensemble learning models that predict the yields of ethylene and propylene. Four single-model AI techniques and four ensemble paradigms were developed using experimental data derived from the catalytic cracking experiments of various crude oil fractions in the advanced catalyst evaluation reactor unit. The temperature, feed type, feed conversion, total gas, dry gas, and coke were used as independent variables. Correlation matrix analyses were conducted to filter the input combinations into three different classes (M1, M2, and M3) based on the relationship between dependent and independent variables, and three performance metrics comprising the coefficient of determination (R²), Pearson correlation coefficient (PCC), and mean square error (MSE) were used to evaluate the prediction performance of the developed models in both calibration and validations stages. All four single models have very low R² and PCC values (as low as 0.07) and very high MSE values (up to 4.92 wt %) for M1 and M2 in both calibration and validation phases. However, the ensemble ML models show R² and PCC values of 0.99–1 and an MSE value of 0.01 wt % for M1, M2, and M3 input combinations. Therefore, ensemble paradigms improve the performance accuracy of single models by up to 58 and 62% in the calibration and validation phases, respectively. The ensemble paradigms predict with high accuracy the yield of ethylene and propylene in the catalytic cracking of crude oil and its fractions.

The utilization of non-precious nickel-based catalyst in increasing ammonia dissociation for COx-free hydrogen production was investigated. Typically, Co, La and basic metal oxides (Na, K, Ba) promoters were synthesized with nickel over acidic gamma alumina support. The main objective of the study was to modify the acid-base surface of catalyst structure thereby increasing ammonia dissociation activity. The catalytic activity for ammonia decomposition was strongly influenced by the addition of Na and K oxide promoters over 15 %Ni/Al2O3 resulting in moderate-stronger basic sites suitable for ammonia conversion. The addition of Na and K oxides showed a clear trend in tuning the trimetallic catalyst and significantly reducing the amount of strongly adsorbed hydrogen on the catalyst surface. This results in higher ammonia conversion which increased as a function of temperature to 32.4 %, 67.5 % and 95.3 % at 430 ᵒC, 485 ᵒC, and 533 ᵒC, respectively. Ammonia conversion using promoters was stable with no degradation of performance and the conversion increased with the decrease in WHSV. The catalytic reactivity over trimetallic catalysts was systematically influenced by their basic-acidic property that promoted ammonia dehydrogenation on the surface of nickel oxide-based catalyst.

The catalytic cracking of heavy atmospheric gas oil (AGO) has been investigated to study the effect of ZSM-5 zeolite crystal size on the selectivity to light olefin in the absence and presence of steam. Dodecane (used as model compound) and heavy AGO feed streams were utilized to study the influence of changing pore shape selectivity when comparing cracking performance by nano and micro ZSM-5 zeolites. The zeolites were characterized using BET, XRD, NMR, NH3-TPD and Py-FTIR. In the presence of steam, the short pores length nano ZSM-5 crystals showed enhanced catalytic cracking activity and selectivity to light olefins. The nano ZSM-5 catalyst promoted higher selectivity to light olefins through β-scission while reducing the extent of hydrogenation reactions towards the formation of liquefied petroleum gas components (LPG). In contrast, the long pores length of micro ZSM-5 tended to favor the production of more naphtha, kerosene and LPG through hydrogen transfer routes, resulting in lower selectivity to light olefins. The resulting propylene/ethylene (P/E) ratios were altered by the type of feed used, cracking reaction temperature, influence of steam and catalyst crystal size. Specifically, higher P/E ratio was achieved over nano ZSM-5 zeolite, especially with the cracking of heavy AGO feed in the presence of steam, due to an increase of monomolecular reactions through β-scission cracking mechanism.

Chemical upcycling of waste plastics into high-value-added products is one of the most effective, cost-efficient, and environmentally beneficial solutions. Many studies have been published over the past few years on the topic of recycling plastics into usable materials through a process called catalytic pyrolysis. There is a significant research gap that must be bridged in order to use catalytic pyrolysis of waste plastics to produce high-value products. This review focuses on the enhanced catalytic pyrolysis of waste plastics to produce jet fuel, diesel oil, lubricants, aromatic compounds, syngas, and other gases. Moreover, the reaction mechanism, a brief and critical comparison of different catalytic pyrolysis studies, as well as the techno-feasibility analysis of waste plastic pyrolysis and the proposed catalytic plastic pyrolysis setup for commercialization is also covered.