Chemical Engineering & Technology最新文献

The percentage of solvents that volatilized during each phase, from spraying to drying, was estimated. The percentage clearly differed depending on the vapor pressure of solvents in coating material. When the coated material was dried without flash-off time after spraying, the concentration of organic components in a drying oven was considerably higher. A Pt/Co₃O₄–CeO₂ catalyst was highly effective for exhaust gas from the drying oven containing high concentrations of the aromatic hydrocarbons and fatty acid esters, achieving a conversion of around 90 %.

Mini-reactors have the advantages of good transportability, easy operability, low cost, and facile scalability. In the liquid–liquid two-phase system with a large density difference, gravitational force plays a significant role in shaping fluid hydrodynamics in mini-channels. The flow characteristics of the sulfuric acid/C₄ hydrocarbon (H₂SO₄/C₄) system in a mini-channel were studied via computational fluid dynamics model under different flow directions to illustrate the gravity effect. The results show that vertical downward direction is more beneficial for forming C₄ droplets. The C₄ droplets display M-shaped axial velocity, vortex-driven interface renewal, and a wriggling motion with periodic shape change. The interface deformation and disturbance during the movement can intensify mass transfer of acid–hydrocarbon two-phase system significantly. These findings deepen the fundamental understanding of gravity effect on multiphase flows in mini-scale devices.

Enameled steel chemical reactor equipment. © gen_A@AdobeStock

The aim of this article is to investigate the effect of alkali metals on the NH₃-SCR performance of Fe–Mn/TiO₂ catalysts and the poisoning mechanism at 30–170 °C. The catalysts without poisoning, with different kinds of alkali metal poisoning, and with different potassium content poisoning were prepared by impregnation method. The activity tests showed that Na, Ca, and K poisoning could lead to different degrees of catalyst deactivation. Characterization analyses showed that alkali metal poisoning decreases the catalyst specific surface area and pore size, reduces the content of surface–active components Mnⁿ⁺, Feⁿ⁺, and (Oα), and reduces the reduction capacity of Mnⁿ⁺ and Fe³⁺. Mechanism analysis showed that K would reduce the reactivity of Lewis acid sites on the catalyst surface, thus leading to a decrease in the intensity of denitrification reactions conducted via the L–H and E–R mechanisms.

In comparison to the traditional study of micropolar fluid that enhances the transport properties, it also favors augmenting the fluid temperature for the interaction of diversified physical quantities. The proposed model for the flow of micropolar nanofluid is improved for the integration of radiating heat and dissipative heat through a permeable medium along with Joule and Darcy dissipation. The present model is reported in the dimensional form that is transformed into ordinary with corresponding standard form using similarity rules. Further, a numerical method combined with the shooting and Runge–Kutta technique is utilized to get the results of each of the profiles. The parameters contributing the fluid flow profiles are deployed graphically, and the rate coefficients are also visualized.

Integration of solar-assisted vapor absorption refrigeration (SVAR) with multi-effect evaporator (MEE) is investigated for supply and optimal energy distribution. A solar collector area of 9000 m² was necessary to make the SVAR provide MEE with sensible heat to operate at prescribed operating conditions. For better management of the available energies, three MEE variants were proposed. All variants can achieve perfect energy utilization with zero residue only if the MEE feed rate is prudently adjusted. The highest attainable recovery ratio and performance ratio are 38 % and 2.0, respectively. Two MEE variants suffer from chilling energy shortage when the last effect temperature (T_bn) is less than 41 °C, whereas another variant undergoes the same issue when T_bn exceeds 41 °C. SVAR can provide sufficient feed preheating and condenser cooling over a range of temperature drop per effect between 1 and 5 and a range of feed rate of 10–50 kg s⁻¹ except at sporadic extreme conditions.

The Baeyer-Villiger oxidation of cyclohexanone to ε-caprolactone (ε-CL) faces challenges in catalyst efficiency and mechanistic clarity. This work develops a Fe–O–Sn composite oxide catalyst for green ε-CL synthesis via O₂/benzaldehyde, achieving 99.99 % conversion and selectivity at 120 mmol scale with 5-cycle stability. Kinetic studies reveal first-order dependencies on cyclohexanone and benzaldehyde. Characterization confirms uniform Fe–Sn distribution and mesoporous structure. The lower activation energy of benzaldehyde indicates preferential peroxybenzoic acid formation, facilitating ε-CL production. This study offers a scalable catalytic system and kinetic framework for industrial application.

Flowing water-in-oil (W/O) emulsions is one of the main problems in oil production lines, due to the exponential increase in viscosity with increasing water content. The formation of these kinetically stable emulsions is provided by natural petroleum surfactants that migrate to the water/oil interface, preventing coalescence between drops. The injection of chemical demulsifiers appears as an alternative to solve these problems. In order to study this alternative, a polyol-based demulsifier was injected into a pipeline circuit with W/O emulsions flowing inside it. The results showed that the injection of demulsifier at concentrations above 500 ppm in emulsions with high water content (above 40 %) promoted the anticipation of the phase inversion point. At lower concentrations (below 300 ppm), there was only a reduction in the apparent viscosity, with a maximum reduction of 32 %. The rheological analysis showed that the demulsifier made the droplet interface less rigid, favoring coalescence.

Supported carbon mixed matrix membranes (CMMMs) were prepared by incorporating 0.1 %, 0.5 %, and 1 % clinoptilolite zeolite (CZ), a natural inorganic material, into polyetherimide (PEI), following by pyrolysis. The CZ exhibited adequate thermal stability to withstand pyrolysis, and, for the first time, this zeolite was applied to CMMM development. The CZ affected the interlayer spacing and the organization of the carbon structures. Moreover, the adsorption properties of CZ influenced performance of CMMM. Membranes containing 0.1 % and 0.5 % CZ exhibited high selectivity for O₂/N₂ and CO₂/CH₄, but a decrease in selectivity was observed in the membrane containing 1 % CZ. The membrane prepared with 0.5 % CZ demonstrated the most favorable permeability-selectivity relationships for O₂/N₂ and CO₂/CH₄ separations, with selectivities of 23 and 110, respectively. This work highlights the potential of using a natural-origin material to optimize the performance of carbon membranes for gas separation.

The isomerization of glucose catalyzed by attapulgite (ATP) modified by MgCl₂ was investigated. The catalytic performance of ATP on glucose isomerization was significantly enhanced after MgCl₂ modification (Mg-ATP), achieving a fructose yield of 36.5 % and a selectivity of 90.2 % in an aqueous system at 120 °C for 1 h. Combined with the characterization results, it could be concluded that the microstructure of ATP has been changed after MgCl₂ modification, leading to an increase in surface area and the number of weak basic sites, which are beneficial for the glucose isomerization reaction.