(106g) Synthesis, Characterization of Vanadia/Titania-Based Catalysts and Their Performance in Ammonia Remediation

Hao Chen^1,3, Raquel Portela⁴,Wei Han¹, Pedro Avila⁴,Miguel A. Bañares⁴, King Lun Yeung^1,2*

¹Department of Chemical and Biomolecular Engineering, ²Division of Environment, ³Nano Science and Technology Program, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P.R. China

⁴ Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, 28049, Madrid Spain

*Corresponding author: kekyeung@ust.hk

Division: 20 Catalysis and Reaction Engineering Division

Subdivision: 20037 Applied Environmental Catalysis

Format: Oral Presentation

Abstract:

Ammonia is an important source of malodors that are becoming more prevalent in urban cities. Indeed, malodor is a rampant environmental pollution problem that is prominent in the places that transport, process and store organic and biological wastes (e.g., drainage and sewers, waste and recycling stations, wastewater and solid waste treatment facilities, incineration plants and landfills). Discomfort breathing, eye and throat irritations and headaches are common complaints related to malodor. Long-term exposure is known to cause olfactory dysfunction, sleep and eating disorders and even behavioral problems in people. Vanadium oxides are known to catalyze many partial oxidation reactions including the partial oxidations of alkanes, olefins and alcohols, and more recently, the selective oxidation of NH₃ to N₂. The versatility of the vanadium oxide catalyst is attributed to the facile transition among the various active vanadium oxide species and the formation of oxygen vacancies that facilitates the transport and storage of reactive oxygen species. In this study, a series of NH₃ oxidation catalysts were prepared from a suspension of UV100 and ammonium vanadate meta in DDI water via rotary evaporation to obtain well dispersed vanadia-titania powder. These obtained catalysts were tested via the reactions with a wide concentration range of NH₃ from 50 ppm to 4370 ppm in air. The results show near 100% conversion for low concentrations of NH₃ and still high reaction rate with moderate conversion for high concentrations of NH₃. The catalysts can tolerate to high humidity without the generation of any NO_x species. The structure, composition and chemistry of the catalyst were charactrized by XRD, Raman, TEM, SEM, nitrogen physisorption, XPS, XPF and in situ/ operando spectroscopic techniques. It is concluded thatvanadium oxides are present mainly as monomeric and polymeric species on these catalysts even when the V-loading approach theoretical monolayer coverage. Operando spectroscopic method is instrumental in revealing how the vanadium species evolve during the reaction and how they relate to the reaction behavior.