Petroleum Chemistry最新文献

A series of RHO zeolites were synthesized by steam-assisted dry gel conversion (SAC). The effects of autoclave water volume, crystallization time, crystallization temperature, and ultrasonic treatment on the phase composition and particle size of RHO zeolites were investigated for the first time. Using X-ray diffraction analysis, scanning electron microscopy, and energy dispersive spectroscopy, the SAC method was found to synthesize high-purity and high-crystallinity RHO zeolites. The optimum synthesis conditions include a temperature of 140°C, a reaction time of 48 h, and 0.5 mL of water per 1 g of dry gel.

Isotherms were recorded for the adsorption of chicken egg lysozyme and bovine serum albumin (BSA) on MFI zeolites with different concentrations of acid sites (from 15 to 1000 μmol/g). The maximum adsorption capacities were evaluated, and the correlation between acid site concentration and protein adsorption capacity was identified. The sample with the highest acidity exhibited the highest adsorption capacity. The protein adsorption reduced the total acid site concentration by 20–30% and simultaneously increased the relative content of weak sites. Furthermore, the adsorption affected the IR spectra of the proteins.

The possibility of amines synthesis from a mixture of carbon dioxide, hydrogen, and ammonia in a slurry reactor in the presence of bifunctional catalytic suspensions 1% Fe–1% Co–0.5% Al₂O₃–0.02% BaO was studied. In the presence of the suggested catalysts, primary amines with up to 16 carbon atoms in the chain are formed with 52–60% feed conversion in the yield reaching 2.4 g per 1 m³ of the initial syngas. The effect of the catalyst activation conditions on its activity in the tandem synthesis of higher amines and on the chain length in the aliphatic amines formed was determined: the increasing of pretreatment time with hydrogen from 2 to 4 h, the maximum feed conversion shifts toward lower temperatures by 40°C with a simultaneous significant increase of С₁₃–С₁₆ monoalkylamines content in the reaction products.

MOF-5 is a classic metal-organic framework (MOF) crystal. However, synthesis of high-quality crystals usually requires an expensive N,N′-diethylformamide (DEF) solvent, and a high molar ratio of a raw material (Zn²⁺ : BDC^2– = 3‒5 : 1). More critically, its extreme instability against water vapor has caused researchers to do not use it. In this study, we achieved some important breakthroughs by using inexpensive N,N′-dimethylformamide (DMF) solvent and meticulously optimizing synthesis parameters combined with a specialized micro-open solvothermal method. With a reduced molar ratio of a raw material (1.47 : 1), we successfully synthesized crystals exhibiting excellent phase structure and morphology, high surface area, _outstanding water vapor stability, and strong CO₂ adsorption capacity. The results show that the DEF replacement with DMF and reduction of the raw material molar ratio from 3 : 1 to 1.47 : 1 provides an increase of the BET surface area from ~935 to 2388 m²/g, and an improvement of the CO₂ adsorption capacity from ~0.8 to 2.5 mmol/g (298 K, 100 kPa). Breakthrough curves reveal that in simulated separation experiments for the flue gas and natural gas containing low CO₂ concentrations (10‒20%), the dynamic separation selectivity for CO₂/N₂ reaches 22, while that for CO₂/CH₄ remains stable at 4. Notably, the selectivity remained nearly unaffected by the pressure variation; this phenomenon is promising for enhancing the capture and purification of a low-concentration CO₂ from the flue gas and natural gas. It is important that the improved MOF-5 crystals prepared under optimal synthetic conditions maintained the stable phase structure and morphology even after 14-day exposure to humid air (relative humidity >70%), successfully overcoming the challenge posed by a water vapor.

The depletion of low-viscosity crude oil reserves necessitates the production of heavy, high-viscosity crude oil. However, transportation of heavy oils is challenging due to their high viscosity. This study aims to develop a sustainable solution to reduce the viscosity of heavy oil by exploiting oscillating bubbles within the fluid. This is because traditional methods by drag reduction additives cause environmental pollution and dangerous emissions, in addition to their high economic cost. An ultrasonic device with a constant power of 150 W and a frequency of 40 kHz was used at different temperatures, while the ultrasonic irradiation time was 10 and 15 min. A viscosity reduction rates (VRR) factor was used to determine changes in viscosity. The viscosity reduction rate (VRR) was at its best at an irradiation time of 10 min under the present experimental conditions and at different temperatures, where it reached more than 36%. At 70°C, when the irradiation time reached 15 min, the viscosity of the oil samples increased. The results indicate that the cavitation, thermal, and mechanical effects of ultrasound can break the long carbon chains of crude oil and form short chains, thus reducing the viscosity. The increase in viscosity after increasing the irradiation time can be attributed to the re-association between molecules. The technique is promising as an eco-friendly and efficient method for heavy oil viscosity reducing alternative that reduces chemical usage and preventing carbon emissions.

This study examines the impact of equipping a real heat exchanger in a slurry bubble column SBC on instantaneous and local heat transfer coefficients IHTC and LHTC, as well as the overall heat transfer coefficient U, employing advanced heat transfer techniques. The experiments were conducted in a 0.15 m inner diameter Plexiglas SBC with varying gas flowrates Ug (0.14–0.35) m/s at several radial sites along the column’s diameter (±0.18, ±0.46, and ± 0.74) and three axial locations (H/D = 2, 3 and 4). To simulate the industrial Fischer–Tropsch bubble column reactor FT-BCR, a real heat exchanger consisting of 18 copper tubes, each with a diameter of 0.16 m, were vertically installed, occupying 25% of the column cross-sectional. Glass beads with an average size of 150 μm were used loading up to 40% volume to represent the solid phase. The results demonstrated that both, LIHTC and U, showed significant decreases with increasing gas flow rates at all radial and axial positions. Moreover, the LIHTC near the wall notably decreased compared to the central zone by about 82% at the radial location and about 74% at the axial location. The obtained results and data contribute to understanding the impact of vertical tubes on heat transfer in a slurry bubble column reactor SBCR. Furthermore, the data obtained can validate reactor models, computational fluid dynamics CFD programs, and simulations, thereby improving the design and scale-up of these reactors.

Activated carbon was prepared from walnut shells (WS-AC) to study the adsorption mechanism of Congo red (CR) dye in an aqueous solution. The adsorbent was characterized using a Fourier transform infrared spectrophotometer (FT-IR), a scanning electron microscope (SEM), and X-ray diffraction (XRD). The effect of experimental factors, including pH, CR initial concentration, adsorbent dosage, and adsorption time were investigated. 98% of CR dye removal was achieved at pH 2 for 25 mg/L of CR concentration at a 1 g adsorbent dosage at 25°C. The Langmuir and Freundlich models were employed to analyze the data and find the most suitable isothermal model for achieving CR adsorption over WS-AC. The pseudo-first-order (PFO) and pseudo-second-order (PSO) models were used to characterize the CR adsorption kinetics onto the WS-AC adsorbent surfaces. The Langmuir equilibrium model was the most accurate representation of the experimental data. The maximum Langmuir adsorption capacity of WS-AC was determined to be 61.6 mg/g. The kinetic analyses demonstrated that the adsorption of CR over WS-AC followed a pseudo-second-order kinetic model, as evidenced by the high R² values (0.999) found. This work has shown that walnut shell activated carbon is an effective and economical adsorbent for removing Congo red anionic dyes from wastewater.

The raw material used in this study represented fluid catalytic cracking slurry oil (FCC). Fractionated oil (HDAO) was extracted via supercritical continuous deasphalting. Subsequently, mesophase was prepared by a thermal condensation reaction in a reactor using FCC and HDAO. The mesophase formation in FCC and HDAO under varying reaction conditions was analyzed using polarized light microscopy, X-ray diffraction (XRD), and Raman spectroscopy. The study was focused on examining the raw material composition and the effects of different conditions on the mesophase content and the flow domain texture distribution. The results demonstrated that supercritical continuous deasphalting effectively removed the most solid impurities, asphaltene and resin. Furthermore, the presence of an appropriate amount of aliphatic short side chains and 2‒3 ring cycloalkane structures, along with a large amount of four-ring short side-chain aromatic structures provided a formation of a large-domain, high mesophase content, and well-textured mesophase in a short time at high temperatures.

This study presents FCC-BL, a novel material that can be converted into the mesophase pitch, characterized by a wide-area streamlined optical texture and large domain texture, via the direct thermal polycondensation under optimized reaction conditions. It has an ordered microcrystalline structure and great yield overcoming the difficulty of synthesizing mesophase pitch with a good optical texture in the traditional FCC slurry; Mesophase pitch with a specific anisotropic structure is produced by a continuous screening of reaction conditions and thermal polycondensation, and its properties and structure are characterized and analyzed using the polarizing microscope, FTIR, ¹H NMR, and XRD. The experimental results reveal that mesophase pitch with the optimal performance is obtained at a temperature of 420°C, a pressure of 2 MPa, and a reaction time of 6 h. The resulting mesophase pitch product exhibits a streamlined texture in a large watershed, with a softening point at only 233°C and low impurity content, that makes the material highly suitable for the production of carbon fibers.