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Using pseudoboehmite and cerium nitrate as raw materials, a cerium dioxide-doped alumina support was prepared by the hot oil column method. Subsequently, with platinum nitrate and palladium nitrate solutions as precursor salts, the active components were loaded onto the supports via the incipient wetness impregnation, followed by an activation treatment, thus obtaining platinum-palladium bimetallic catalysts for hydrocarbon elimination in zero-air generators. The catalyst was characterized by XRD, BET, SEM, TEM, XPS, and Raman spectroscopy. The results showed that the as-prepared supports possess a large specific surface area, and the noble metals Pt and Pd are uniformly distributed on the support surface. After activation treatment, the structural stability and catalytic reaction activity of the catalysts are significantly enhanced. Performance tests simulating the actual operating conditions of zero-air generators show that the catalysts exhibit excellent hydrocarbon elimination capability: when the inlet methane concentration is 50 ppm, the outlet methane content can be reduced to below 10 ppb. Moreover, no obvious attenuation of catalyst activity is observed after a 1000-h long-term stability test, which meets the practical application requirements of zero-air generators. Full article

Background: Safe and efficient disposal of millions of tons of pepper sauce waste (PSW) can be a challenge to pepper sauce manufacturers that are concerned about creating environmental hazards from the processing (e.g., preservative salt and vinegar) and intrinsic (e.g., the pungent capsaicins) ingredients. It will be immensely beneficial to process these waste materials before they go to disposal. This work presents integrated approaches for a complete utilization of waste materials by removing and recovering valuable by-products and/or ingredients while succeeding to minimal to zero hazards. Methods: Laboratory- and pilot-scale extraction processes were used to demonstrate the recovery of intrinsic compounds from PSW to pungent pepper oil. Flash chromatography was then applied to isolate the pungent capsaicins out of the pepper oil, thus generating a no-heat pepper oil. Results: By processing the waste materials, a number of valuable by-products with various yield percentages were produced. They included (1) hot red pepper oil (RPO, 8.0% v/w), (2) no-heat pepper residue (NHPR, 25.3% w/w), (3) no-heat red pepper oil (NHRPO, 4.0% v/w), (4) capsaicinoids (0.8% w/w), and (5) capsaicin (0.4% w/w). The optimum processing conditions for products 1, 2, and 3 include extracting the waste materials with 95% ethanol twice, each lasting three hours. The optimal isolation conditions of flash column chromatography to obtain products 4 and 5 include the use of the pre-packed chromatography column 130 g Redisep C18, preparing the sample concentration to 100 mg/mL, eluting with aqueous ethanol, and detecting capsaicins at a wavelength of 228 nm. Conclusions: An integrated approach is offered for the complete utilization of PSW. It not only turns organic food waste into numerous new commodities but also significantly reduces the volume and degree of potential environmental hazard to the disposal sites. Full article