Heterogeneous catalytic wet air oxidation of refractory organic pollutants in industrial wastewaters: a review.

The paper reviews solid-catalyzed oxidation and reduction processes for the treatment of wastewater that contains small concentrations of toxic compounds and for which separation is not economical while biological treatment is not feasible. Specifically, the objectives are (1) to understand the interactions between catalytic materials and various pollutants, (2) to provide a database for catalyst selection, and (3) to assess the potential of these processes for commercialization. The review suggests the following well-investigated solutions:  (1) Supported metal (Ru/CeO2, Pt/CeO2, and Ru/C) and metal oxides (CuO−ZnO−CoO, MnO2/CeO2, CoO/Bi2O3, and V2O5/Al2O3) are the most promising catalysts for the destruction of refractory organic compounds with nearly 100% selectivity to CO2; (2) CoO/CeO2 and MnO2/CeO2 are the most active catalysts for ammonia oxidation at temperatures of 263−400 °C; (3) activated carbon, preferably in the presence of copper ions, is an active catalyst for the oxidation of cyanides and ...

Catalytic Abatement of Water Pollutants

Wet air oxidation: past, present and future

Catalytic wet-air oxidation processes: A review

A concise review of relevant experimental observations and modeling of high-pressure trickle-bed reactors, based on recent studies, is presented. The following topics are considered:  flow regime transitions, pressure drop, liquid holdup, gas−liquid interfacial area and mass-transfer coefficient, catalyst wetting efficiency, catalyst dilution with inert fines, and evaluation of trickle-bed models for liquid-limited and gas-limited reactions. The effects of high-pressure operation, which is of industrial relevance, on the physicochemical and fluid dynamic parameters are discussed. Empirical and theoretical models developed to account for the effect of high pressure on the various parameters and phenomena pertinent to the topics discussed are briefly described.

https://crelonweb.eec.wustl.edu/ReactionEngineeringCourse/Day-8.pdf

High-Pressure Trickle-Bed Reactors: A Review

Rates of oxidation of dilute, aqueous solutions of acetic acid were measured at 252° to 286°C and 67 atm in liquid full and trickle-bed reactors packed with ferric oxide catalyst particles. Predicted global rates and conversions indicated that localized vaporization and liquid channeling could affect trickle-bed performance.

Oxidation of acetic acid solutions in a trickle-bed reactor

An active catalyst for the oxidation of acetic acid solutions

A sorption enhanced-steam methane reforming (SE-SMR) process was investigated in a countercurrent gas–solid trickle flow reactor packed with regularly stacked catalyst. The stacked catalyst was made of corrugated Pt/Ni/Al2O3 plates in the form of static mixers. Experiments were carried out in a temperature range of 550–600 °C, total pressure of 4.0 bar, and water to methane ratio of 4.0 in the reactor feed. Within the investigated conditions, experimental results offered a solid proof of concept for new continuous SE-SMR operation for production of hydrogen where sorbent can be regenerated separately from the catalyst. Experimental data were reasonably well described by a plug flow model for both the gas and solid phases. The mathematical model was further used to optimize the continuous SE-SMR operation: it could be demonstrated that the level of the hydrogen purity in the reactor exit stream could be controlled by a multistage reactor consisting of alternating catalytic active and stainless-steel inert ...

High Purity Hydrogen with Sorption-Enhanced Steam Methane Reforming in a Gas–Solid Trickle Bed Reactor

Void fraction distribution in a bisectional bubble column reactor

The sorption reaction CaO–CO2 was examined in a countercurrent gas–solid trickle flow reactor with regularly stacked packing at T = 500–600°C, pCO2 = 40–50 kPa, solid-phase fluxes S = 0.3–0.5 kg m−2 s−1, and CaO particles of 500–710 μm in size. Sorption kinetics was evaluated by thermogravimetric (TG) technique. The random pore model was used for the description of the carbonization reaction. Hydrodynamic characteristics of gas–solid trickle flow were estimated at room temperature and ambient pressure. Plug flow model of both gas and solid-phase, with the parameters obtained from TG and hydrodynamics experiments, satisfactorily described the sorption process in countercurrent gas–solid trickle flow reactor. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1601–1612, 2015

Janez Levec

Papers

Oxidation of acetic acid solutions in a trickle-bed reactor

An active catalyst for the oxidation of acetic acid solutions

High Purity Hydrogen with Sorption-Enhanced Steam Methane Reforming in a Gas–Solid Trickle Bed Reactor

Void fraction distribution in a bisectional bubble column reactor

Countercurrent gas–solid trickle flow reactor with structured packing: Hydrodynamics and CaO–CO2 reaction