Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) - Volume 18, Issue 1, 2025

A series of Cu-montmorillonite clay composites (MtCs), prepared through cation exchange and wet impregnation with varying amounts of copper, were tested for the direct oxidation of methane to methanol.

The catalysts were characterized using several analytical techniques, including surface area BET, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Ammonia Temperature-Programmed Desorption (NH3-TPD), and pyridine desorption, followed by Fourier Transform Infrared (FTIR) spectroscopy. Catalytic tests were conducted at various temperatures and pressures using hydrogen peroxide as the oxidizing agent.

The characterization results indicated the incorporation of copper species did not significantly modify the clay composite morphology. The TEM images of the samples with low copper content (0.8 Cu wt.%) showed the copper particles to be uniformly distributed. Conversely, for the higher copper content samples (3.5 Cu wt.%) prepared by wet impregnation, the copper particles were distributed around the montmorillonite clay composites. It has been observed that silica (MtC-Si) and aluminum (MtC-SiAl) montmorillonite clay composites have exhibited notable differences in acid site strength and distribution, influencing the dispersion and type of copper species being active for direct oxidation of methane to methanol.

The findings indicated that the well-dispersed copper species, favored by the structure MtCs, resulted in enhanced catalytic activity for methane’s oxidation to methanol.

Palm oil and waste cooking oil undergo functionalization by introducing epoxy groups onto their double bonds, which are subsequently opened to yield hydroxyl groups.

The objective of this paper is to produce epoxidized hybrid oleic acid with an applied heterogeneous catalyst for polyol feedstock.

In situ peracids are generated during the reaction by mixing an acid (commonly acetic acid or formic acid) with hydrogen peroxide. Range Kutta 4^th Order Method of numerical integration was used to develop kinetic modeling for reaction based on the mathematical model.

After 40 minutes of epoxidation reaction, the relative conversion to the oxirane percentage reached its maximum of 51%. Fourier transform infrared spectroscopy detected an absorption peak at 3300 cm^-1, suggesting the presence of a hydroxyl group.

Epoxidation of palm oil and waste cooking oil using in situ peracids is an efficient method for converting unsaturated fatty acids into epoxidized oils, which have significant industrial applications.

Centrifugal pump is widely used in industrial production as a key fluid conveying equipment. The transient characteristics during its start-up process may lead to vibration, noise and efficiency loss. Therefore, it is very important to optimize the start-up process.

Optimize the structural parameters of the centrifugal pump, with the initial pulse values of both the head and efficiency as the optimization objectives, to enhance its transient performance.

In recent years, thanks to advances in patents and technology, centrifugal pump optimization through numerical simulation and experimental comparison has become more reliable. This article selects design parameters through sensitivity analysis, and then establishes a BP neural network and optimizes it using genetic algorithm.

The optimized head pulse value is reduced by 4.39 m, and the efficiency pulse value is reduced by 5.65%. Make the start-up process of centrifugal pump more stable.

Among the parameters that affect the stability of the centrifugal pump start-up process, it can be obtained that the three factors of impeller outlet width, blade outlet angle and blade wrap angle have the greatest influence on the fluctuating head and efficiency of the centrifugal pump.

Refractory linings of cement rotary kilns are subjected to severe thermomechanical stresses of cranking, ovality, tyre hooping/migration, and uneven thermal distribution. An insistent demand is to discover the significance of spinel, hercynite, galaxite, and chromite in magnesia refractories, as well as their flexibilizing mechanisms.

The objectives are to compare the fracture behavior of magnesia–spinel, –hercynite, –galaxite, and –chromite refractories and to unveil the flexibilizing mechanisms of different spinels.

The wedge splitting test is carried out to produce various fracture parameters. Their flexibilizing mechanisms are studied by performing microstructural observations and analyses.

Various fracture parameters are obtained, including specific fracture energy, brittleness number, characteristic crack length, and thermal-shock resistance parameter. Generally, magnesia–hercynite bricks and magnesia–galaxite bricks have demonstrated the prominent advantages of fracture resistance, which are more flexible than magnesia–spinel bricks and magnesia–chromite bricks.

The flexibility of magnesia–spinel bricks is attributed to microcracks generated from different thermal behavior between spinel grains and surrounding periclase, which is recognized as the thermal-expansion mismatch mechanism. In magnesia–hercynite and magnesia–galaxite refractories, the active-ion-diffusion mechanism is predominant beyond similar microcracks, to drive the flexibility by the continuous diffusion of Fe²⁺, Mn²⁺, and Mg²⁺ during high-temperature burning and using processes. In magnesia–chromite bricks, the pore rims contribute to the flexibility as a silicate-migration mechanism, after silicate envelopes first arise around chromite grains and then vanish into the surrounding magnesia by the suction of capillary force during the burning process.

At present, natural gas and crude oil are significant for the national economy, and their safe transportation is crucial. The integrity of pipelines is the key to ensuring this goal.

We take X100 pipeline as the research object and use ANSYS software to complete finite element simulations of three types of pipeline models: double external defect, double internal defect and double internal and external defect.

ANSYS software was adopted to study three types of pipeline models: double external defect, double internal defect and double internal and external defect. Firstly, the way defect parameters (defect depth and defect length) affect pipeline failure pressure is evaluated. Then, the failure pressure calculation results are fitted with formulas using MATLAB software, and the accuracy and applicability of the fitting formulas are verified.

For the three types of double defect pipeline models, namely double external defect, double internal defect, and internal and external defect, in terms of the impact of defect depth, failure pressure decreases with increasing defect depth. In terms of the impact of defect length, the failure pressure decreased as the defect length increases. The overall average error for the three pipeline models between MATLAB fitting formula results and three standards results are 5.25%, 7.07%, 7.43%, respectively, a relatively low level of error, indicating the MATLAB fitting formula has high reliability and accuracy. The sum of squared correlation coefficients (R2) for the three pipeline models are 0.9190, 0.97837, and 0.97797, respectively, indicating the fitting formula has a high degree of fitting. The serial numbers with pressure ratios greater than 1 for the three pipeline models are 67, 92, and 98, respectively, indicating the double external defect pipeline model performs the best, followed by the double internal defect pipeline model, and the double internal and external defect pipeline model performs the worst.

These findings can be applied to improve the assessment of failure pressure in X100 pipelines, leading to more effective maintenance and inspection strategies.