Current Issue : January-March Volume : 2023 Issue Number : 1 Articles : 5 Articles
Through the impregnation method, Ag catalysts with different support (such as TiO2 and γ-Al2O3) were prepared and then tested for catalytic oxidation of formaldehyde (HCHO) at low temperatures. The Ag/TiO2 catalyst exhibited strong catalytic performance, converting HCHO to CO2 and H2O at around 95˚C. However, the Ag/Al2O3 catalysts showed much lower activity and reached 100% conversion at 125˚C. The Ag-based catalysts were next characterized by several methods (XRD, TEM, FT-R, BET and H2-TPR). Results of characterization revealed that support dramatically impacts the size and dispersion of Ag particles. The XRD analysis showed the existence of different peaks of the silver on the surface of Al2O3 in the contrast with TiO2 no specific peaks exist. Therefore, the size of the Ag particles and their dispersion are the most important factors that affect their catalytic performance for formaldehyde oxidation. In terms of catalytic performance for HCHO oxidation, the Ag/TiO2 catalyst possesses the best Ag dispersion, as well as the smallest Ag particle size....
Traditional onefold data-driven methods for fault detection in complex process industrial systems with high-dimensional, linear, nonlinear, Gaussian, and non-Gaussian coexistence often have less than satisfactory monitoring performance because only a single distribution of process variables is considered. To address this problem, a hybrid fault detection model based on PCA-KPCA-ICAKICA- BI (Bayesian inference) is proposed, taking into account the advantages of principal component analysis (PCA), kernel principal component analysis (KPCA), independent component analysis (ICA), and kernel independent component analysis (KICA) in terms of dimensionality reduction and feature extraction. Foremost, this paper proposed a nonlinear evaluation method and divided the feature variables into Gaussian linear blocks, Gaussian nonlinear blocks, non-Gaussian linear blocks, and non-Gaussian nonlinear blocks by using the Jarque–Bera (JB) test and nonlinear discrimination method. Each division was monitored by the PCAKPCA- ICA-KICA model, and finally the Bayesian fusion strategy proposed in this study is used to synthesize the detection results for each block. The hybrid model helps in evaluating variable features and bettering detection performance. Ultimately, the superiority of this hybrid model was veried through the Tennessee Eastman (TE) process and the Continuous Stirred Tank Reactor (CSTR) process, and the fault monitoring results showed an average accuracy of 85.91% for this hybrid model....
Based on the Soave–Redlich–Kwong equation of state, empirical correlations for the K-values of N2, CO2, H2S, C1, and C2 are proposed. Complementarily, the binary interaction coefficients involving the plus fraction, C7+, were optimized by fitting into 131 experimental data from the literature. The criterion to select the form of the empirical correlations was based on the identification of the major dependencies of the equilibrium constants on the system variables (e.g., pressure, temperature, and composition). For most of the experimental data, the saturation pressure calculated via the empirical correlations is in excellent agreement with those reported from the laboratory. The empirical correlations cover a variety of temperatures (128–314°F), pressures (313–6880 psi), and compositions (N2: 0.0–1.67%; CO2: 0.0–9.11%; H2S: 0.0–3.68%; C1: 5.63–74.18%; C2: 0.84–12.45%; C7+: 10.72–83.2%). The proposed correlations are useful for rapid vapor-liquid equilibrium calculations during the compositional modeling of petroleum reservoirs....
The present study successfully produced a highly effective and stable organ phosphorus-doped tungsten trioxide (P-WO3) photocatalyst by a combination of hydrothermal and postcalcination methods. The crystallites, morphologies, and optical properties of the produced WO3 and P-WO3 crystals were investigated. The results indicated that P was consistently doped into theWO3 lattice in a pentavalent-oxidation state (P5+). Additionally, charge carrier traps capable of accepting photoelectrons were created. Additionally, the optical band gap was reduced from 2.4 to 2.33 eV. The degradation of methyl blue by photocatalysts was utilized to evaluate the photocatalytic performance of the synthesized P-WO3 samples at varied P concentrations (MB). The sample containing 6% -P-WO3 exhibited the best photocatalytic performance, degrading 96 percent of MB in 120 minutes, which was more than four times faster than the pure WO3 sample. The practicality of the synthesized P-WO3 was determined using samples from two residential wastewater treatment plants. When treating real wastewater with low organic matter concentrations, the P-WO3 demonstrated strong photodegradation performance. The creation of hydroxyl radicals (OH) and photographycreated holes (h+) could be the key protagonists of photocatalytic activity in the P-WO3....
This study was focused on the synthesis of activated carbon from a waste tire and the enhancement of its specific area by a demineralization technique that can be used for the removal of methylene blue dye (MB). Maximum MB removal (89.41%) was attained at an impregnation ratio value of 0. A maximum yield (42.65%) was found at 48 h. Waste tire-based activated carbon (WTAC)’s ability to remove MB was increased by large values up to an impregnation time of 24 h. WTAC has a maximum MB removal of 90.13% at 4M of KOH. The sample had a surface area of 53m2/g. This sample was demineralized by using NaOH and H2SO4 in a 1 :1 ratio, and the surface area was enhanced to 257m2/g. In the demineralization process, a massive decrement of metals from the waste was seen; for each metal, namely, Zn2+, Al3+, Ca2+, and Mg2+, 43.79%, 32.45%, 27.95%, and 6.843% reductions were achieved, respectively. After this process, the maximum removal of MB was found at 1.2 g adsorbent dosage, 120 min, pH 8, the temperature of 20°C, and an initial dye concentration of 10 mg/L. The adsorption mechanism revealed that the process of adsorption happens at a specific site of homogeneous adsorption on the surface of the adsorbent. The kinetics study showed that the adsorption process of the dye is mainly affected by the chemical reaction....
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