Petroleum Chemistry最新文献

Hierarchical Al-BEA zeolites were prepared by hydrothermal treatment of a concentrated reaction mixture containing a highly dispersed silicon source. The hierarchical zeolites obtained consist of aggregated crystallites and contain, along with zeolite micropores, also intercrystallite mesopores. With a decrease in the H₂O/Si ratio from 15 to 5.5 and in the Si/Al ratio from 12.5 to 10, the crystallite size decreases to 13 nm. This is accompanied by an increase in the mesopore volume and in the external and total specific surface area of the samples. The catalytic properties of the hierarchical zeolites in the α-pinene isomerization were studied. The initial rate of the α-pinene consumption increases with an increase in the concentration of strong Brønsted acid sites and is the highest for the commercial Al-BEA zeolite with the ratio Si/Al = 12.5. The α-pinene conversion increases with an increase in the external specific surface area of the zeolites and reaches 91% after 24 h of the reaction for the hierarchical zeolite with the ratio Si/Al = 9, prepared in the concentrated reaction mixture. The selectivity of camphene formation decreases and the selectivity of limonene formation increases with an increase in the Brønsted-to-Lewis acid site ratio. The highest camphene and limonene yields, equal to 45 and 31%, respectively, are reached when using the sample with the most developed mesoporosity and the Brønsted-to-Lewis acid site ratio of 0.9.

Micropore diffusion limitations impair the performance of SAPO-11-supported bifunctional catalysts in the hydroisomerization of long-chain n-paraffins (C₇₊), reducing their activity, selectivity, and stability. These diffusion constraints can be mitigated by introducing secondary porosity and reducing the crystallite size. This study investigates the effect of the silica content (varied via the SiO₂/Al₂O₃ molar ratio) on these parameters. The physicochemical properties of the synthesized samples were characterized by XRD, SEM, ²⁹Si MAS NMR, NH₃-TPD, and some other methods. Increasing the SiO₂/Al₂O₃ ratio was shown to reduce the size of primary nanocrystals and generate a well-developed mesoporous structure. At SiO₂/Al₂O₃ ratios ≥ 0.3, the extent of silicon incorporation and the concentration of acid sites reach a maximum, while a decrease in crystallinity was observed. The most developed hierarchical porous structure, featuring an external surface area of 67 m²/g and a mesopore volume of 0.19 cm³/g, was achieved at a SiO₂/Al₂O₃ ratio of 0.1. In the hydroisomerization of n-hexadecane, the sample synthesized with a SiO₂/Al₂O₃ ratio of 0.3—which exhibited an optimal combination of high acidity and small nanocrystal size—achieved the highest conversion and i-C₁₆ selectivity. Therefore, fine-tuning the silica content is an effective strategy for the targeted design of high-performance hydroisomerization catalysts.

The effect of the weight hourly space velocity of methanol on the deactivation of SAPO-34 silicoaluminophosphate in methanol conversion to hydrocarbons has been investigated, and the nature of coke deposits formed on completely deactivated zeolite samples in the course of operation in different reactors has been examined. The deactivation order with respect to methanol is 1 in fluidized-bed, and slurry reactors, while it is 1.2 in the fixed-bed reactor. The presence of polydimethylsiloxane as the reaction medium in a slurry reactor decreases the time of the stable catalyst operation by a factor of 2 relative to the fluidised-bed reactor irrespective of the feed rate. The specific conditions at which different types of reactors demonstrate a more stable operation in this process have been calculated.

Zeolite ZSM-48 is an efficient acidic catalyst support for the hydroisomerization of higher (C₁₆₊) n-paraffins, but its industrial application is hindered by the high cost of conventional structure-directing agents (SDAs). This study develops a more economical synthesis method using hexamethylenediamine (HDA) as an affordable SDA. A series of high-crystallinity zeolite samples (SiO₂/Al₂O₃ = 160–200) were synthesized hydrothermally. After loading with 0.5 wt % Pt, their physicochemical properties and catalytic performance were evaluated in the hydroisomerization of n-hexadecane at 3.0 MPa. The initial alkali content in the reaction gel was identified as a critical parameter controlling crystallization selectivity, crystal morphology, and crystallinity. The sample synthesized with low alkali content exhibited the highest performance, achieving 90% n-hexadecane conversion at 320°C with a yield of desired isomers up to 62%. This demonstrates the high potential of HDA for crystallizing selective ZSM-48 and for preparing promising catalysts for the hydroisomerization of higher n-paraffins.

The second part of the review (Bruter, D.V. and Konnov, S.V., Petr. Chem., 2025, vol. 65, pp. 331–368) is dedicated to the advances in the development of propane dehydrogenation catalysts based on cobalt-, gallium-, indium-, and zinc-containing zeolites. The existing strategies of the synthesis of materials based on molecular sieves are analyzed. In some cases, to reflect more completely recent advances in the development of metal-containing zeolite catalysts for dehydrogenation of lower alkanes, examples concerning ethane dehydrogenation, which is performed under harsher conditions are also presented, as well as oxidative dehydrogenation of lower alkanes with CO₂. Particular attention is paid to studies of structure–property and synthesis–structure relationships. A brief conclusion summarizing the main results and unresolved problems is provided for each catalyst type in the end of the corresponding section. Conclusions regarding the most promising strategies for the development of industrial catalysts of new generation are presented in the final part of the review.

This review provides an analysis of the physicochemical properties and catalytic performance of ZSM-48 zeolites prepared using various inorganic reagents, templates, and seeds under varying synthesis conditions (e.g., reaction temperature and time). The paper discusses the catalytic performance of these zeolites in various reactions, including cracking, hydroisomerization, and methanol-to-hydrocarbons (MTH) conversion.

Hierarchical Al-BEA zeolites were prepared by hydrothermal treatment of the reaction mixture containing highly dispersed Aerosil A-300 as a silicon source without alkali metal cations and additional templates for the mesopore formation. The material with the most developed mesoporosity is formed by concentrating the reaction mixture to the H₂O/Si molar ratio of 5.5. The catalytic properties of the hierarchical materials prepared and commercial zeolite in benzene alkylation with propylene were studied. The samples tested exhibit 88–91 wt % cumene formation selectivity. The hierarchical zeolite prepared from the reaction mixture with the H₂O/Si ratio of 5.5 ensures the highest propylene conversion and exhibits the highest stability in alkylation. This zeolite has the highest mesopore volume, the highest external specific surface area, high concentration of strong Brønsted acid sites, and relatively low content of Lewis acid sites.

Density functional theory (DFT) is the most widely used method of chemical calculations of the structure of atoms that has rapidly gained popularity, two groups of pyrimidine ring derivatives were prepared, the first group is 4-(4-aminophenyl-6-phenyl)pyrimidin-2(1H)-one derivative by adding groups (‒NO₂, ‒Cl, ‒Br, ‒OH), and the second group 4-(4-aminophenyl-6-phenyl)pyrimidin-2(1H)-thione derivatives adding the same groups to study the inhibition efficiency of corrosion, these results show were able to find the theoretically calculated inhibition efficiency value that will increase or decrease the inhibition efficiency, the inhibition efficiency of pyrimidine-1 was measured to make it standard for 4-(4-aminophenyl-6-phenyl)pyrimidin-2(1H)-one derivatives, the inhibition efficiency was improved to (80.962%) as in pyrimidine-4. For 4-(4-aminophenyl-6-phenyl)pyrimidin-2(1H)-thione derivatives, the inhibition efficiency of pyrimidine-6 was measured to make it standard for these derivatives, and the inhibition efficiency was set to (83.838%) for pyrimidine-8. which reinforces that the presence of the hydroxyl group among the groups (nitro-, chloro-, bromo-) was the best in improving the inhibition efficiency of the derivatives of pyrimidine derivatives.

Wastewater usually is treated by using a variety of physical, chemical and biological methods to remove phosphorus and nitrogen from it. This paper examined an experimental investigation to assess the removal of nutrients from synthetic wastewater using a lab-scale Bardenpho process. This study aims to address the impact of hydraulic retention time (HRT) on the nutrients removal efficiency at various internal recycle ratio by using enhanced Bardenpho process. A modified Bardenpho process consists of five reactors (anaerobic, first anoxic, first aerobic, second anoxic, second aerobic) with a secondary settling tank to separate the biomass before to discharge in order to accomplish significant nitrogen and phosphorus removal. The nitrate was recycled into the first anoxic chamber (IR 1), first aerobic chamber (IR 2), and second anoxic chamber (IR 3) in that order after oxidizing in the aeration chamber. Hydraulic retention time of 9.5, 13.5 and 17.5 h were shown to have an effect on the biological reduction of nitrogen and phosphorus using enhanced Bardenpho process. Inlet chemical oxygen demand (COD), total nitrogen (TN), and PO₄ concentrations of 413, 35, and 15 mg/L, respectively, were used to operate at each hydraulic retention time. The HRT of 17.5 h and IR 1 attended maximum removal efficiency of 77.86% for TN at IR 1 and aerobic/anoxic ratio ratio of 1.65, and 68.33% for TP at IR 1 and aerobic/anoxic ratio of 2. While the highest elimination efficiency for COD was 94.92% at IR 1 and total HRT of 17.5 h when the aerobic/anoxic ratio ratio is 2.

This study explores the potential of vacuum residue (VR) as an unconventional and renewable source of global transportation fuel. The primary aim is to investigate the cracking of Iraqi VR using an economically feasible and environmentally friendly geopolymer catalyst. Two types of metakaolin, red (designated G1) and white (designated G2), were mixed with alkaline activators to synthesize geopolymers with a hierarchically porous structure (containing interconnected pores of varying sizes). Following synthesis, the geopolymers were subjected to activation through hydrochloric acid (HCl) treatment. Finally, thermal treatment at 750°C for 2 h was applied to the geopolymer powders. This process yielded red kaolin-based geopolymer G1* and white kaolin-based geopolymer G2*. The extensively characterized using various techniques including XRF, XRD, FE-SEM, FTIR, and BET. Significant differences in Si/Al ratios and iron content were observed between the red and white geopolymers. The white geopolymer showed annite-1M phase, while the red geopolymer showed the existence of a zeolite phase, according to XRD analysis. Further investigation using an FE-SEM revealed that both materials had uniformly distributed, different amorphous morphologies. BET analysis subsequently revealed significant differences in surface area between the red geopolymers (60.89 m²/g) and white geopolymers (19.42 m²/g). Cracking the vacuum residual involved utilizing a geopolymer catalyst within a fixed-bed reactor. The resulting hydrocarbon liquid product, collected to a volume of 17 mL, underwent analysis using Gas Chromatography-Mass Spectrometry (GC-MS). The analytical results obtained from GC-MS provide strong evidence for the effectiveness of the white geopolymer catalyst in the conversion of vacuum residue and producing light petroleum fractions. Notably, the white geopolymer catalysts generated 47% more gasoline products than the 30% yield achieved with red geopolymer catalysts. The vacuum residue obtained from the Al-Doura petroleum refinery in Baghdad, Iraq, exhibited a waxy texture, and black color, and contained heavy hydrocarbons with high molecular weights. This residue is known as Doura Vacuum Residue (VR). Interestingly, the red geopolymer catalysts produced gasoline products of higher quality.