Petroleum Chemistry最新文献

Abstract

Gas-liquid separators often encounter the challenge of liquid carry-over, where small liquid droplets become entrained in the produced gas stream. This phenomenon can lead to foaming and reduced capacity in downstream absorption processes, as observed in Iraq’s Khor Mor gas-condensate processing plant. To assess whether liquid carry-over contributes to the foaming issue in the sweetening tower, this study analyzed the liquid droplet size distribution in the gas phase and the gas/liquid separation efficiency of the upstream Alpha, Bravo #1, Bravo #2, and Charlee separators feeding the tower. The analysis was conducted by using the industry-standard process software, Horizontal Vessel and ProSeparator correlations within Aspen HYSYS v.14. The study revealed that Alpha, Bravo #1, and Bravo #2 separators were unable to eliminate all liquid droplets within the specified size, failing to achieve the required efficiency. In response, the study proposes a vertical scrubber design with a standard mesh mist extractor, applying the Arnold–Stewart semi-empirical procedure. The design demonstrated a gas/liquid separation efficiency of 99% under current and future conditions. These findings suggest that the proposed design can serve as an optimal solution to control liquid carry-over, maintain high gas/liquid separation efficiency, and prevent foaming, even with an increase in the vessel inlet flow rate over time.

Half-sandwich titanium complexes, specifically Cp*TiCl₃ and Cp*Ti[O(2,6-ⁱPr₂-Ph)]Cl₂, were investigated as catalytic precursors for the synthesis of ethylene/propylene copolymers and ethylene/propylene/5-ethylidene-2-norbornene terpolymers. For this purpose, a variety of activators were tested: modified polymethylaluminoxane; boron-containing compounds such as B(C₆F₅)₃ and Ph₃CB(C₆F₅)₄ in combination with triisobutylaluminum (TIBA); isobutylaluminoxane (IBAO), and isobutylaluminum aryloxide (2,6-^tBu₂,4-Me-PhO-)AlⁱBu₂ (Al_BHT). In the copolymerization of ethylene and propylene, the catalysts exhibited high activity when activated by MMAO-12 and TIBA+Ph₃CB(C₆F₅)₄ but low activity with TIBA+B(C₆F₅)₃ and Al_BHT. With IBAO as an activator, these catalysts were found to be totally ineffective. The catalysts exhibited low activity in terpolymerization. It was further revealed that more than one type of active sites was generated in the catalytic systems: these sites were responsible for simultaneous formation of low-molecular-weight and ultrahigh-molecular-weight polymers. The composition of the copolymers as well as their thermophysical and physicomechanical properties were shown to depend on the type and composition of the catalytic system.

The influence of the severity of reaction conditions on the promotional effects of tin in bimetallic Pt–Sn/γ-Al₂O₃ catalysts in the propane dehydrogenation was studied over a wide range of reaction conditions (550–600°C, H₂/C₃H₈ = 0.4–1.5 mol/mol). The catalysts containing 0.5 wt % Pt with variable (0–1.0 wt %) Sn loading were prepared by sequential impregnation and characterized by N₂-physisorption, TPR, TPD, EDX, and TEM techniques. When 0.25 wt % tin was added to the Pt/γ-Al₂O₃ catalyst, at H₂/C₃H₈ molar ratios of 0.8 and 1.5 and all temperatures, a sharp (up to 100%) increase in the propylene selectivity was observed. The propylene yield vs. Sn loading curves showed maxima near the Sn/Pt weight ratio of 1 independently of operating conditions. Upon addition of the optimum amount of Sn, the first-order decay rate constant decreased from 0.15 to 0.066 h^–1 at 550°C and H₂/C₃H₈ = 0.4, which roughly corresponded to doubling of the catalyst lifetime under this condition. The promoting effect of Sn on the catalyst performance was more pronounced under more severe reaction conditions required for higher propane conversions, i.e., at higher temperatures and lower H₂/C₃H₈ ratios in the feed.

The kinetics of the adsorption of lysozyme and bovine serum albumin (BSA) onto zeolites of BEA and MFI structural types and onto silica adsorbents of the same structural types was studied. The rate constants of the reversible adsorption step were calculated. The adsorption rate constants are 0.4–0.8 L mol^–1 s^–1 for lysozyme and 0.7–1.4 L mol^–1 s^–1 for BSA. The rate constants of the desorption from the surface of all the samples are in the range from 1.3 × 10^–5 to 1.6 × 10^–5 s^–1 for both enzymes.

The study describes toluene ethylation using TsVM zeolite (SiO₂/Al₂O₃ = 40) and a series of TsVM-based catalysts modified with rare-earth metals. To investigate the effects of the type and loading of rare-earth metals in the HTsVM catalyst on the selectivity towards total ethyltoluenes and p-ethyltoluene, the reaction was carried out in a continuous-flow fixed-bed reactor at atmospheric pressure and temperatures of 300–400°C. The HTsVM was modified with praseodymium, ytterbium, and holmium nitrates. The physicochemical and textural properties of the catalysts were characterized by XRD, FTIR spectroscopy, NH₃-TPD, and low-temperature nitrogen adsorption. The specific surface area, acidity, total pore volume, and mesopore volume were found to decrease with an increase in the holmium loading of the catalyst. The zeolite catalysts loaded with 4.0–5.0 wt % Ho exhibited optimum stability and high p-ethyltoluene selectivity (79.5–81.4%) in combination with adequate toluene conversion (19.4–20.3%).

The study compares the elemental composition of asphaltenes with the parameters of hydrocarbon biomarkers and Precambrian insoluble organic matter (OM) of the Aldan–Maya depression. The elemental composition of the asphaltenes was found to depend on the pyrolytic characteristics of the OM. Using asphaltene compositions in combination with biomarker parameters, the genetic and catagenetic features of difficult-to-study objects such as Precambrian bitumens can be characterized more accurately and reliably. The elemental composition of the asphaltenes was shown to correlate with the aromatic parameters that reflect the OM maturity. In contrast, the parameters of the asphaltenes show essentially no correlation with biomarker data for the saturated components.

The physicochemical properties of a series of catalysts based on granulated Na-Yh zeolite with the hierarchic (micro–meso–macro) pore structure (Na-Yh, HNa-Yh, MgO/Na-Yh, La₂O₃/Na-Yh, TiO₂/Na-Yh) and the activity and selectivity of these catalysts in isophorone aromatization were studied. MgO/Na-Yh and La₂O₃/Na-Yh zeolites with high content of basic sites and low content of Brønsted acid sites are the most effective in the synthesis of 3,5-dimethylphenol: The 3,5-dimethylphenol formation selectivity reaches 63–69% at 87–94% isophorone conversion. In the presence of Na-Yh zeolite containing both acid and base sites, the prevalent reactions are isophorone isomerization and synthesis of trimethylbenzenes. The modification of Na-Yh with titanium oxide leads to an increase in the content of acid sites on the TiO₂/Na-Yh surface and to the prevalence of the aromatization to form trimethylbenzenes. In the presence of HNa-Yh containing a set of the strongest Brønsted and Lewis acid sites, isophorone transforms into a mixture of polymethylbenzenes.

The paper describes synthesis of ZSM-5 zeolite using two amorphous synthetic aluminosilicates prepared by different methods: one involved precipitation from solutions of sodium silicate and aluminum sulfate, and the other was based on sol–gel synthesis using tetraethyl orthosilicate and aluminum nitrate. The method for the preparation of amorphous aluminosilicates was shown to affect the morphology, dispersion, and porous structure of ZSM-5 crystals.

Using a combination of XRD, ²⁷Al and ³¹P MAS NMR, SEM, TEM, N₂ low-temperature adsorption–desorption, and IR spectroscopy of adsorbed pyridine, the effects of gel preparation conditions on the properties of the SAPO-11 molecular sieves crystallized from the gels were investigated. It was demonstrated that the crystal morphology and the characteristics of secondary pores of SAPO-11 molecular sieves can be controlled by adjusting the sequence in which the initial components are mixed during gel preparation. The synthesized micro–mesoporous SAPO-11 samples exhibited high selectivity in the hydroisomerization of n-hexadecane.

The study proposes a novel approach for the synthesis of granular MCM-22 zeolite with a hierarchical micro–meso–macroporous structure. This approach is based on the crystallization of zeolite granules consisting of powdered MCM-22 and synthetic amorphous aluminosilicate. The synthesized material had 97% crystallinity and volumes of micro-, meso-, and macropores of 0.18, 0.22, and 0.46 cm³/g, respectively. The H-form of the hierarchical MCM-22 exhibited high activity and selectivity in dimerization of α-methylstyrene.