More alloying on silica: Controlling the stoichiometry and achieving a high degree of alloying of metals at ultrasmall scales for catalysis can be difficult. Double complex salts, formed by a cation like Pd(NH ₃ ) ₄ ²⁺ and an anion like IrCl ₆ ²⁻ , should be excellent precursors but are poorly soluble and difficult to adsorb directly on metal oxide surfaces. Ding et al. show that sequentially adsorbing the cations and anions from organic solvents onto a silica surface, followed by heating in hydrogen, creates well-mixed nanoparticles, most less than 3 nanometers in diameter, for a variety of alloys. These materials were then tested as catalysts for acetylene hydrogenation to ethylene. Science , this issue p. 560

Raman Spectroscopy is a well-known method for identifying molecules by their spectroscopic “fingerprint”. In Surface Enhanced Raman Scattering (SERS), the presence of nanometallic surfaces in contact with the molecules enormously enhances the spectroscopic signal. Raman enhancing surfaces are often fabricated lithographically or chemically, but the throughput is low and the equipment is expensive. In this work a SERS layer was formed by the self-assembly of silver nanospheres from a hexane suspension onto an imprinted thermoplastic sheet (PET). In addition, the SERS layer was transferred and securely bonded to other surfaces. This is an important attribute for probes into solid specimen. Raman spectra were obtained with Rhodamine 6G (R6G) solution concentrations ranging from 1 mm to 1 nm. The methods described here produced robust and sensitive SERS surfaces with inexpensive equipment, readily available materials, and with no chemical or lithographic steps. These may be critical concerns to laboratories faced with diminishing funding resources.

The presence of toxic, corrosive, and environmentally harmful sulfur compounds within natural gas streams necessitates their removal to ensure compliance with fuel quality standards and regulations. Previous studies into MMOs (mixed metal oxides) as adsorbent or catalysts for sulfur compound removal have generally focused upon hydrogen sulfide (H₂S); however, few studies have assessed the removal of organic sulfur compounds like mercaptans. The purpose of this research is to investigate the effects of various preparation routes on the performance of supported metal-oxide catalysts that remove mercaptans from natural gases; specifically, filtration-based and evaporative based catalyst synthesis methods were investigated. A set of different catalysts; Mn, Cu, Zn, Ni and a composite (Mn-Cu-Zn-Ni) were prepared using filtration or evaporation solvent removal in this research and characterized by BET, FTIR, XRD, SEM, EDS and XPS, and their adsorption performance was assessed through fixed-bed breakthrough experiments under representative operating conditions (25°C, 200 psi, 36 mL/min). The results demonstrate that catalysts prepared via evaporation consistently exhibit greater sulfur compounds adsorption performance compared to catalysts prepared through filtration method, primarily due to enhanced retention of active metal species and improved surface accessibility. As confirmed from the characterization, all these improvements result from the fact that the evaporation method enhances the interaction between the metals and oxygen (FTIR); increases the amount of oxides formed as well as improves their distribution (XRD); provides access to more available metal surfaces (XPS/EDS); and creates pore structures and morphologies that are more open and accessible (SEM/BET). Among the catalysts studied, the Mn and Cu catalysts prepared by evaporation achieved the highest breakthrough times 1410 minutes and 1350 minutes, respectively, exceeding the performance of a commercial benchmark catalyst with breakthrough time of 1200 minutes under identical conditions. These findings demonstrate that the evaporation method enables more effective utilization of metal-oxygen active sites and significantly enhances sulfur adsorption capacity. Overall, this work establishes evaporation as a superior and scalable preparation strategy for metal oxide catalysts and provides important structure performance insights for the design of cost-effective catalyst for industrial natural gas desulfurization, particularly for the removal of organic sulfur compounds from natural gas.

The removal of sulfur compounds such as ethyl mercaptan from natural gas remains a critical challenge due to their detrimental effects on downstream processes, catalyst poisoning, and environmental emissions. In this study, a series of halloysite-supported transition metal oxide catalysts was synthesized and evaluated for the removal of sulfur compounds from natural gas at 25 °C, 200 psi, and 36 mL/min, using 0.5 g of the catalyst. The nanotubular structure and dual surface chemistry of halloysite promote enhanced metal dispersion and improved mass transfer. Single-metal (manganese, copper, zinc, and nickel) catalysts were developed and tested, after which a multi-metal oxide (base) catalyst comprising a composite of the single metals (Zn-Cu-Mn-Ni) was developed as a base catalyst to combine adsorption-active and redox-active functionalities, and its performance was further enhanced by the addition of palladium as promoter. A combination of analytical techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), provided evidence that highly dispersed metal oxide phases were formed and the halloysite structure was preserved. XPS data showed the presence of oxidation states of metals that were active (Zn²⁺, Cu²⁺, Ni²⁺, Mn³⁺/Mn⁴⁺ and Pd²⁺), an indication of a redox-active surface for sulfur interaction. Results from the breakthrough experiments showed that the base catalyst significantly improved sulfur removal compared to single-metal catalysts, while the Pd-promoted catalyst exhibited the highest performance, with a breakthrough time of 630 min. Palladium was incorporated at low loading as a promoter, enhancing adsorption performance while maintaining a favorable balance between efficiency and material cost. This enhancement is attributed to synergistic interactions between adsorption-active sites and redox-active species, as well as improved electron transfer facilitated by palladium. The results demonstrate that rational design of multi-metal oxide catalysts supported on naturally occurring halloysite provides an effective and scalable approach for sulfur removal from natural gas, with strong potential for industrial applications.

The presence of toxic, corrosive, and environmentally harmful sulfur compounds within natural gas streams necessitates their removal to ensure compliance with fuel quality standards and regulations. Previous studies into MMOs (mixed metal-oxides) as adsorbents or catalysts for sulfur compound removal have generally focused on hydrogen sulfide (H₂S); however, few studies have assessed the removal of organic sulfur compounds such as ethyl mercaptans. The purpose of this research is to investigate the effects of various preparation routes on the performance of supported metal-oxide catalysts that remove ethyl mercaptans from natural gas; specifically, filtration-based and evaporation-based catalyst synthesis methods were investigated. A set of different catalysts—Mn, Cu, Zn, Ni, and a composite (Mn-Cu-Zn-Ni)—were prepared using filtration or evaporation solvent removal in this research and characterized by BET, FTIR, XRD, SEM, EDS, and XPS, and their sulfur-removal performance was evaluated through fixed-bed breakthrough experiments under representative operating conditions (25 °C, 200 psi, 36 mL/min). The results demonstrate that catalysts prepared via evaporation consistently exhibit greater sulfur adsorption performance compared to catalysts prepared through filtration, which is consistent with improved surface oxide exposure. Structural characterization further showed that evaporation-assisted preparation promoted improved surface oxide development, greater surface heterogeneity, and more accessible surface morphologies. Among the investigated catalysts, evaporation-prepared Mn and Cu catalysts achieved the highest breakthrough times of approximately 1410 min and 1350 min, respectively, exceeding the commercial benchmark catalyst (1200 min) under identical operating conditions. These findings demonstrate that the evaporation method enables more effective utilization of surface metal-oxide active sites involved in sulfur adsorption and surface redox interactions. Overall, this work establishes evaporation as a superior and scalable preparation strategy for metal oxide catalysts and provides important structure-performance insights for the design of cost-effective catalysts for industrial natural gas desulfurization, particularly for the removal of organic sulfur compounds such as ethyl mercaptan from natural gas.