In this work, 1%Pd/gamma-Al2O3 catalysts modified with poly(4-vinylpyridine) (P4VP), polyacrylamide (PAM), and polyacrylic acid (PAA) were synthesized and evaluated for allyl alcohol hydrogenation. The effect of P4VP content was systematically investigated by varying the polymer loading, followed by comparison of the catalytic properties of the modified catalysts with that of the unmodified 1%Pd/gamma-Al2O3 catalyst. The synthesized catalysts were characterized by TGA, IR spectroscopy, XRD, TEM, XPS, SEM/EDS, and viscosimetry to evaluate their structural, morphological, surface, and elemental properties. TEM analysis revealed that low P4VP loading preserved small Pd nanoparticles (3.9 nm), whereas higher polymer loadings promoted particle growth to 7.7 nm. All catalysts achieved complete conversion of allyl alcohol. At 5 wt.% polymer loading, the P4VP-modified catalyst exhibited a slightly higher hydrogenation rate than the PAA- and PAM-modified catalysts. Decreasing the P4VP content from 5 to 3 and 1 wt.% increased the hydrogenation rate from 8.3 & times; 10-6 to 13.9 & times; 10-6 and 22.9 & times; 10-6 mol/s, respectively, while propanol selectivity increased from 64 to 65 and 71%. The 1%Pd-P4VP(1%)/gamma-Al2O3 catalyst exhibited higher catalytic activity than the unmodified 1%Pd/gamma-Al2O3 catalyst and maintained good stability over 20 consecutive substrate additions. These findings demonstrate that the catalytic behavior of polymer-modified 1%Pd/gamma-Al2O3 catalysts depends on the balance between polymer loading, Pd nanoparticle size, and active site accessibility.
To enhance the high-temperature rutting resistance, fatigue performance and low-temperature cracking resistance of base asphalt, and promote the resource utilization of industrial solid waste, this study took 70# asphalt as the base asphalt and selected nano-montmorillonite (MMT) and fly ash (FA) as composite modified fillers. A series of composite modified asphalt samples was prepared with MMT:FA mass ratios of 1:2, 1:3 and 1:4 and total filler contents of 3%, 5% and 7%, respectively. Conventional physical tests, dynamic shear rheometry (DSR), multiple stress creep recovery (MSCR), linear amplitude sweep (LAS) and bending beam rheometry (BBR) were adopted to systematically evaluate the pavement rheological properties. The microscopic modification mechanism was revealed by thin-layer chromatography with flame ionization detection (TLC-FID) and gel permeation chromatography (GPC). The results show that MMT-FA composite filler can significantly reduce the penetration, increase the softening point, and greatly enhance the high-temperature rutting factor, creep-recovery rate and fatigue life of asphalt, while its influence on low-temperature performance is controllable. For the optimal group, S5, the rutting factor rises by 42.6% at 64 degrees C, and the fatigue life increases by 58.3% under 5.0% strain compared with the base asphalt. With the increase in filler content, the high-temperature and fatigue performance of asphalt increases first and then slows down, while the low-temperature stiffness rises gradually. Microscopic analysis indicates that the intercalation and strong adsorption of MMT restrict the light components of asphalt and increase the proportion of macromolecules, and FA plays the roles of particle filling and skeleton support. The two fillers synergistically optimize the colloid structure and molecular distribution of asphalt. Based on rheological properties and microscopic mechanism, the optimal ratio is 1:3 for MMT:FA with a total content of 5%, under which the composite modified asphalt achieves the best comprehensive pavement performance and can meet the requirements of heavy-load traffic and areas with large temperature differences. The research results can provide experimental and theoretical support for the material design, performance optimization and engineering application of MMT-FA composite modified asphalt.
The long-term preservation of earthen wall heritage in Shanxi largely depends on the stability of its rammed earth walls. In this study, the ancient city wall site of Guoyang in Shanxi is taken as a case study. Samples are collected from four directional sections (brick, mortar, and rammed earth), and a nonlinear dynamic finite element method (FEM) with horizontal impact loading is applied, combined with microscopic analyses (SEM, XRF, XRD), to investigate the deterioration mechanisms and structural responses of the brick wall surface. The results show that (1) under identical stress, the north wall exhibits smaller displacement (2.942 & times; 10-2 mm) than the south wall (4.058 & times; 10-2 mm), indicating greater lateral stiffness and deformation resistance; (2) the rammed earth particles on the north side show the highest uniformity (CV = 0.4981), while those on the west side display the greatest dispersion (CV = 0.9852), revealing pronounced differences in microscopic stability among the different wall orientations; (3) the north-side rammed earth exhibits a composition typical of high-quality traditional ternary lime-soil mixtures, characterized by high SiO2 (47.06%), high CO2 (19.73%), and low Na2O (2.358%); and (4) the durability of the four wall sections varies with distinct deterioration characteristics. Mineral composition and environmental factors jointly contribute to the differences in wall color and surface conditions. This study provides a reference for the conservation and restoration of similar rammed earth heritage sites.
Highlights What are the main findings? What are the implications of the main findings?Highlights What are the main findings? What are the implications of the main findings?Abstract The corrosion of tin amalgam reflective coatings on Qing Dynasty reverse glass paintings has traditionally been attributed to oxidation pathways. No other corrosion types have been reported for this artifact class to date. This study investigated two reverse glass paintings using Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and micro-Raman spectroscopy (Raman). In one sample, the corrosion products are romarchite (SnO), tin tetroxide (Sn3O4), and cassiterite (SnO2), confirming the conventional oxidation pathway. In the other sample, abhurite (Sn21Cl16(OH)14O6) and hydroromarchite (Sn3O2(OH)2) are identified alongside tin oxides. This is the first report of chlorine-bearing corrosion products in Qing Dynasty reverse glass paintings. This finding indicates that the coating was exposed to a high-humidity, chloride-containing environment. The coexistence of chloride-mediated and oxidation-pathway products reflects microenvironmental heterogeneity on the coating surface. Preventive conservation for similar objects should prioritize maintaining a stable relative humidity at approximately 50%, excluding exogenous chloride sources, and avoiding acidic pollutants.
Routine model-based diagnosis of sulfuric acid converters can attribute performance loss to catalyst deactivation, fouling, bypass, or maldistribution before establishing whether routine measurements distinguish these causes. This study develops the Converter Condition Inference Framework (CCIF) for four-bed double-contact SO2 converters, placing a practical identifiability gate before mechanism-specific interpretation. A reported-parameter reaction and energy balance kernel using published feed, kinetics, and physical reaction enthalpy reproduces the industrial benchmark only approximately. An energy balance check indicates that the reported first-bed conversion and temperature require an effective enthalpy of about 1.6 times the physical value under the adopted thermochemical basis. At the reference condition, the uncertainty-scaled local sensitivity matrix has rank 1 for a six-state vector; this result persists across the tested inlet temperature range and rate and heat release perturbations. In the equilibrium-limited reduced model, catalyst activity loss and fouling down to 40% of fresh activity produce no resolvable change in conversion, outlet SO2 slip, or bed temperatures, whereas bypass alters the temperature signature. Even idealized bed-resolved catalyst condition observations raise the rank only to 5. CCIF therefore reports the evidence-supported state class and required measurement upgrades rather than a validated diagnosis. Unit-specific calibration and catalyst-side evidence remain necessary before mechanism-specific maintenance decisions.
