Catalytic Oxidation in Supercritical Water

Abstract

Recently, catalytic oxidation in supercritical water (SCW) has received considerable research attention. The major thrust of this current research effort is attributable to the rapid development of supercritical water oxidation (SCWO) as an innovative wastewater treatment technology. The incentives of catalyst-enhanced processes may include increased reaction rates, reduced residence times and temperatures, and optimized reaction pathways that are otherwise difficult to achieve through noncatalytic processes. However, the databases associated with the use of catalysts in SCWO are limited. The purpose of this paper is to (1) review catalytic enhancement and technology as related to SCWO; (2) analyze effects of SCW on catalysts and catalytic SCWO processes; and (3) present a catalyst development strategy for SCWO-related applications. Catalyst activity and stability (in terms of reaction kinetics, surface phenomena, and phase behavior of catalysts in SCW) are emphasized. The paper presents a useful database, provides guidelines for catalyst selection, and illustrates how effective use of catalyst may enhance SCWO process development.

Carbon materials and catalytic wet air oxidation of organic pollutants in wastewater

“…WAO performance can be improved by the addition of homogeneous [5,6] or heterogeneous [4] catalysts at subcritical conditions or at severe 'supercritical' operating conditions [7,8]. Alternatively, low temperature oxidation processes replace oxygen by stronger oxidants such as O 3 [9,10] or H 2 O 2 [9,11,12] in combination with an energy input to form reactive OH-radicals [13,14].…”

“…Alternatively, low temperature oxidation processes replace oxygen by stronger oxidants such as O 3 [9,10] or H 2 O 2 [9,11,12] in combination with an energy input to form reactive OH-radicals [13,14]. Several reviews on catalytic and non-catalytic WAO [4,5,[15][16][17][18][19], supercritical water oxidation (SCWO) [7,8,[20][21][22] and advanced oxidation processes (AOP) [23][24][25] are now available in literature.…”

“…Over the last 10-15 years, continuous SCWO technology proved to be an extremely powerful treatment for all kinds and concentration range of toxic organic wastewater [7,8,[20][21][22]. Related problems with corrosion and plant plugging due to salt precipitation were solved on laboratory scale leading to new reactor configurations termed hydrothermal burner [49] and Transpiring Wall Reactor [50].…”

Corrosion Properties of Candidate Materials in Supercritical Water Oxidation Process

“…The reaction condition of SCWO usually contained the temperature range of 400 °C~600 °C and pressure range of 24 MPa ~ 28 *Corresponding author; E-mail address: szwang@aliyun.com MPa (2,4,13). The solubility of ionic compound will decrease sharply when the wastewater is heated to supercritical condition.…”

“…However, there is serious corrosion for materials under the harsh working conditions of high temperature, high pressure and strong corrosive anions. The corrosion problem is the main obstacle to the commercialization and large-scale application of SCWO (12,13,(15)(16)(17)(18)(19)(20)(21).…”