Abstract: A process for regenerating a catalyst consisting of a mixed oxide having molybdenum, bismuth and iron used for preparing an unsaturated aldehyde and/or an unsaturated carboxylic acid by catalytically oxidizing propylene, isobutylene and/or tert.-butanol with molecular oxygen in a gas phase, in which the catalyst is regenerated by thermally treating the deteriorated catalyst in an atmosphere of a gas containing molecular oxygen at a temperature of 200 to 500° C., and then thermally treating the catalyst in the presence of a reducing compound at a temperature of 200 to 500° C.

Abstract: The invention relates to a process for removing sulfur particles from an aqueous catalyst solution used to remove hydrogen sulfide from a gas stream (1, 5), comprising the steps of directing a flow of a suspension (12) comprising reduced catalyst solution and sulfur particles to an oxidizer zone (20), where the catalyst solution is regenerated by contacting said suspension with a gas (22) containing oxygen; and removing sulfur from said suspension at least by gravity sedimentation at a bottom (21) of said oxidizer zone (20). According to the invention a flow deflecting means (34) is disposed at least at an outlet (35) for the oxidized catalyst solution leaving said oxidizer zone (20) such as to prevent any turbulent state caused at least by a stream of oxidized catalyst solution leaving said oxidizer zone (20).

Abstract: Degradation of catalyst activity for silicoaluminophosphate catalysts is minimized for oxygenate-to-olefin reaction systems that are exposed to airborne salt concentrations above a threshold value. When airborne salt concentrations above the threshold value are detected, an air intake flow can be diverted into a cleaning flow path and/or an alternative source of regeneration media can be provided.

Abstract: A process for treating a supported epoxidation catalyst comprising silver in a quantity of at most 0.15 g per m2 surface area of the support, which process comprises: contacting the catalyst, or a precursor of the catalyst comprising silver in cationic form, with a treatment feed comprising oxygen at a catalyst temperature of at least 350° C. for a duration of at least 5 minutes; the catalyst; a process for the epoxidation of an olefin; and a process for producing a 1,2-diol, 1,2-diol ether, or an alkanolamine.

Abstract: A mixed metal oxide, which may be an orthorhombic phase material, is regenerated, selectively enriched or selectively poisoned as a catalyst to reduce catalyst aging for the production of unsaturated carboxylic acids, or unsaturated nitrites, from alkanes, or mixtures of alkanes and alkenes, by contacting said mixed metal oxide with a an oxidizing gas such as oxygen, air, steam and combinations thereof is permitted to flow through the catalyst in a regenerator at a temperature of from 300° C. to 600° C. to form said regenerated catalyst.

Abstract: The present invention provides an exhaust gas treatment method including oxidation treatment for converting metallic mercury contained in combustion exhaust gas into mercury chloride; and mercury removal treatment for removing mercury from the combustion exhaust gas by dissolving the mercury chloride in water, wherein a plurality of oxidation catalysts for performing the oxidation treatment are provided, and during the time when the oxidation treatment is performed, at least one of the oxidation catalysts performs catalyst performance restoration treatment without performing oxidation treatment. According to the present invention, the deterioration in mercury removal performance can be restrained even in continuous operation on condition that mercury is oxidized in a low temperature region not higher than 300° C.

Abstract: A process for the preparation of a catalyst which comprises activating a catalyst precursor comprising a cobalt compound and a support with a gas comprising at least 5 mol % of a hydrocarbon.

Abstract: A catalyst system and process for combined cracking and selective hydrogen combustion of hydrocarbons are disclosed.

Abstract: A zeolite and an organic binder are mixed with a solvent to form a paste (302). The paste is then cast or molded (304) into the desired shape. A portion of the solvent is allowed to evaporate from the paste, hardening the getter (306). Getters are often formed in sheets and cut (308) into individual pieces, called dibs, after the sheets have hardened. Even after the getter is hardened, significant amounts of solvent are retained by the getter. The getter is exposed to water vapor which displaces (310) the solvent from the getter. After the solvent is removed, the getter is dried (312) to remove additional water vapor. Because the water vapor does not bind as tightly to the zeolite getter, the water vapor is removed much easier than the solvent. The water may be removed by allowing the getter to dry naturally, or by a vacuum bake process.

Abstract: A process is disclosed for regenerating a hydrocarbon conversion catalyst comprising zeolite L with ozone. The catalyst is contacted with ozone at a temperature of from about 20 to about 250° C. and a concentration of ozone of from about 0.1 to about 5 mol-%. The catalyst may contain coke. The process at least partially restores the activity of the catalyst. The process is particularly useful for reforming and dehydrocyclodimerization catalysts.

Abstract: Disclosed is an apparatus and process for prolonging the residence time of catalyst in a chamber for regenerating catalyst. Spent catalyst, perhaps from an FCC reactor, is introduced into a chamber of a regeneration vessel between lower and higher combustion gas distributors. The velocity of gas from the lower distributor is insufficient to entrain catalyst from the bed, and gas from the higher distributor when combined with gas rising from the lower distributor is sufficient to generate a fast fluidized flow condition. The second distributor elevates the location of the transition from turbulent bed to fast fluidized conditions.

Abstract: A method of cleaning the adsorbent media of a rotary concentrator in-situ while maintaining operation of the concentrator, including directing washing liquid into the sectors in the desorb plenum, then rotating the sectors one full revolution plus at least one sector into the desorb plenum to bring a second sector into the desorb plenum, washing the second sector and repeating the cycle until all of the adsorbent media is washed. The method may also include directing washing liquid into sectors not located in the desorb plenum.

Abstract: The present invention is to solve the problems caused by a conventional method for producing a zinc chloride-loaded support wherein zinc chloride is adsorbed on a solid support in an aqueous solution of zinc chloride. The problems include environmental destruction caused by the treatment of a used aqueous solution of zinc chloride, corrosion to a reactor, a threat to health for workers, deterioration of zinc chloride due to deliquescence thereof, and reduction of specific surface area.

Abstract: A process is disclosed for regenerating a catalyst used in a process for synthesizing hydrocarbons. The synthesis process involves contacting a feed stream comprising hydrogen and carbon monoxide with a catalyst in a reaction zone maintained at conversion-promoting conditions effective to produce an effluent stream comprising hydrocarbons. The regeneration process involves contacting a deactivated Fischer-Tropsch catalyst with a regeneration gas under regeneration-promoting conditions that include a pressure lower than the mean Fischer-Tropsch reaction pressure, for a period of time sufficient to reactivate the Fischer-Tropsch catalyst.

Abstract: Process and device for regeneration of a used absorbent from a desulfurization zone or from the desulfurization of a gas containing sulfur oxides, comprising regeneration simultaneously with filtering of the absorbent, in a reducing atmosphere, wherein partial combustion of a regeneration gas is also carried out upstream from regeneration, the products of the partial combustion being mixed with the used absorbent prior to the regeneration-filtration stage. The absorbent may be, e.g., solid absorbents based on magnesium oxide. The regeneration gas may be hydrogen sulfide and/or a hydrocarbon. For example, H2S can be partially combusted and the products of the partial combustion, including H2S, H2, SO2 and sulfur, mixed with the used absorbent prior to the regeneration-filtration stage.

Abstract: A process for the regeneration of a zeolite catalyst which comprises treating the catalyst thermally in the presence of a gas stream at temperatures above 120° C., the weight-based residence time of the gas stream over the catalyst during the thermal treatment being greater than 2 hours.

Abstract: The present invention relates to a process for the preparation of ?- or ?-unsaturated or saturated carboxylic acids. It relates more particularly to the hydroxycarbonylation of an organic compound comprising a conjugated unsaturation, such as butadiene, by the action of carbon monoxide and water in the presence of a palladium-based catalyst. The carboxylic acids thus obtained are preferably pentenoic acids. According to the invention, the reaction medium after the end of the hydroxycarbonylation stage is treated with hydrogen to reduce the palladium present in the 2+ oxidation state to palladium in the zero oxidation state and the precipitated palladium is recovered.

Abstract: A gas stream containing e.g. molecular hydrogen is used for the regeneration of a catalyst for NOx and SO2 removal from the flue gas of a gas turbine. In order to reduce the consumption of regeneration gas, the gas inlet is located between the SCOSOx catalyst (2) and the SCONOx catalyst (3). The regeneration gas leaves the catalyst chamber upstream of the SCOSOx catalyst and is recycled. For the regeneration of the SCONOx catalyst and to keep SO2 containing gas from entering the SCONOx catalyst, a second regeneration gas inlet is located downstream of the SCONOx catalyst. The regeneration gas entering the catalyst chamber through this port passes the SCONOx (3) and the SCOSOx catalyst (2). The direction of the flow in the SCONOx catalyst can also be reversed. In another example, regeneration gas outlets are located both upstream of the SCOSOx and downstream of the SCONOx catalyst. But, only the regeneration gas from the SCONOx catalyst is recycled.

Abstract: The invention is directed to a method of stabilizing metalloaluminophosphate molecular sieves and catalysts derived therefrom. In particular, the invention is directed to a method of treating such molecular sieves with one or more nitrogen containing compounds having a kinetic diameter greater than the average pore size of the activated molecular sieve and selected from the group consisting of amines, monocyclic heterocyclic compounds, organonitrile compounds and mixtures thereof to chemisorbed and/or physisorbed the compound onto the molecular sieve. The compounds may be easily desorbed before or during use and after storage. The invention is also directed to formulating the molecular sieve into a catalyst useful in a process for producing olefin(s), preferably ethylene and/or propylene, from a feedstock, preferably an oxygenate containing feedstock.

Abstract: The present invention is related to a magnesium oxide particle aggregate with the requirement of a first inflection point diameter is more than 0.30×10?6 to 0.60×10?6 m, a particle void volume is 0.50×10?3 to 0.90×10?3 m3·kg?1, and a micropore volume is 0.04×10?3 to 0.11×10?3 m3·kg?1 in the cumulative intrusion volume curve of said particle by having controlled particle aggregation structure so that the solid phase-solid phase reaction between magnesium oxide and the SiO2 film on the surface can be appropriately controlled.

Abstract: A process is disclosed for regenerating a catalyst used in a process for synthesizing hydrocarbons. The synthesis process involves contacting a feed stream comprising hydrogen and carbon monoxide with a catalyst in a reaction zone maintained at conversion-promoting conditions effective to produce an effluent stream comprising hydrocarbons. The regeneration process involves contacting a deactivated Fischer-Tropsch catalyst with a regeneration gas under regeneration-promoting conditions that include a pressure lower than the mean Fischer-Tropsch reaction pressure, for a period of time sufficient to reactivate the Fischer-Tropsch catalyst.

Abstract: In a fuel reforming apparatus having a reformer for reforming a raw fuel containing a hydrocarbon-containing compound so as to produce a hydrogen-rich fuel gas for use in a fuel cell, a carbon removal process for removing carbon deposited on a reforming catalyst contained in the reformer is executed by controlling the amount of the raw fuel supplied to the reformer and the amount of the oxygen supplied to the reformer so that a ratio of the number of oxygen atoms O supplied to the reformer to the number of carbon atoms supplied to the reformer becomes larger than an appropriate range of the O/C ratio that is to be established during a normal operation of the reformer.

Abstract: An distributor arrangement introduces spent FCC catalyst more uniformly across the dense bed of the regenerator to provide more even contact with regeneration gas in order to avoid hot spots and zones of incomplete combustion. The invention forms a fluidized hopper to collect spent catalyst and a horizontally extended header with multiple horizontally extended outlet arms to place catalyst into the regenerator. The invention may use an aeration means to fluidize the header to further assist catalyst flow. Furthermore, the spent catalyst delivered to the top of the regenerator dense reduces NOx emissions in the flue gas.

Abstract: In operation of an internal combustion engine, exhaust gases of the internal combustion engine are directed through an oxidation catalyzer and thereby heat the catalyzer. Subsequently the engine is stopped, and the catalyzer is regenerated by supplying reducing gas to the catalyzer while the catalyzer is still sufficiently hot for regeneration to occur.

Abstract: A gas stream containing e.g. molecular hydrogen is used for the regeneration of a catalyst for NOx and SO2 removal from the flue gas of a gas turbine. In order to reduce the consumption of regeneration gas, the gas inlet is located between the SCOSOx catalyst (2) and the SCONOx catalyst (3). The regeneration gas leaves the catalyst chamber upstream of the SCOSOx catalyst and is recycled. For the regeneration of the SCONOx catalyst and to keep SO2 containing gas from entering the SCONOx catalyst, a second regeneration gas inlet is located downstream of the SCONOx catalyst. The regeneration gas entering the catalyst chamber through this port passes the SCONOx (3) and the SCOSOx catalyst (2). The direction of the flow in the SCONOx catalyst can also be reversed. In another example, regeneration gas outlets are located both upstream of the SCOSOx and downstream of the SCONOx catalyst. But, only the regeneration gas from the SCONOx catalyst is recycled.

Abstract: A process for preparing a fluorination catalyst using a low pressure activating step followed by a high pressure activating step.

Abstract: The invention is directed to a method of stabilizing metalloaluminophosphate molecular sieves and catalysts derived therefrom. In particular, the invention is directed to a method of treating such molecular sieves with one or more nitrogen containing compounds selected from the group consisting of amines, monocyclic heterocyclic compounds, organonitrile compounds and mixtures thereof to chemisorbed and/or physisorbed the compound onto the molecular sieve. The compounds may be easily desorbed before or during use and after storage. The invention is also directed to formulating the molecular sieve into a catalyst useful in a process for producing olefin(s), preferably ethylene and/or propylene, from a feedstock, preferably an oxygenate containing feedstock.

Abstract: The invention relates to a method for regenerating a used solid absorbent from a desulphurization zone wherein partial combustion of a regenerating gas, regeneration of the absorbent by contacting, in a chamber, said absorbent with the gas effluents derived from the combustion, cooling the gas mixture resulting from regeneration to a temperature higher than the liquid sulphur formation temperature, and filtering the cooled mixture to separate the solid particles of regenerated absorbent from the gas fraction of said mixture is carried out. The invention also relates to an installation for implementing said method.

Abstract: An exhaust emission control regeneration system regenerates a particulate filter by combusting trapped particulate and producing a combustion product from such combustion, and uses the combustion product to assist regeneration of a downstream catalyst, such as CO assisting regeneration of a downstream NOX adsorber, located in sufficiently close proximity to a diesel particulate filter.

Abstract: A process of treating a catalyst composition containing palladium, an inorganic support, and a catalyst component, such as silver and/or a modifier such as alkali metal fluoride, is provided. The process involves contacting a catalyst composition with a first treating agent comprising carbon monoxide under a first treating condition to provide a treated catalyst composition. As an option, such treated catalyst composition can then be contacted with a second treating agent comprising a hydrogen-containing fluid under a second treating condition. The treated catalyst composition can be used in a selective hydrogenation process in which highly unsaturated hydrocarbons such as diolefins and/or alkynes are contacted with such treated catalyst composition in the presence of hydrogen to produce less unsaturated hydrocarbons such as monoolefins.

Abstract: A high temperature water gas shift catalyst comprising iron and at least one promoter is prepared via a method which comprises the preparation of a high purity iron precursor and which uses a nominal amount of water in the catalyst production. The catalyst prepared according to the inventive method is more efficient in hydrogen production under the high temperature water gas shift reaction conditions in a fixed bed test than prior art catalysts of similar composition.

Abstract: A process to regenerate iron-based hydrogen sulfide sorbents using steam. The steam is preferably mixed with hydrogen-containing gas and/or an inert gas, such as nitrogen. In a preferred embodiment, the sorbent is first exposed to the steam and then exposed to a hydrogen-containing gas at regeneration conditions.

Abstract: A method of reactivating a catalyst, such as a solid catalyst or a liquid catalyst. The method comprises providing a catalyst that is at least partially deactivated by fouling agents. The catalyst is contacted with a fluid reactivating agent that is at or above a critical point of the fluid reactivating agent and is of sufficient density to dissolve impurities. The fluid reactivating agent reacts with at least one fouling agent, releasing the at least one fouling agent from the catalyst. The at least one fouling agent becomes dissolved in the fluid reactivating agent and is subsequently separated or removed from the fluid reactivating agent so that the fluid reactivating agent may be reused. A system for reactivating a catalyst is also disclosed.

Abstract: The present invention provides a process and a device for regeneration of a nitrogen oxide storage catalyst in the exhaust system of a diesel engine. The process comprises a first and a second regeneration strategy. The first regeneration strategy is applied when the exhaust gas temperature is above a threshold value and comprises changing the air/fuel-ratio from a lean to a rich value during a first regeneration period. The second regeneration strategy is applied when the exhaust gas temperature is below a threshold value and comprises switching the air/fuel-ratio back and forth between lean and rich air/fuel-ratios, forming a sequence of between 2 and 10 rich pulses and between 2 and 10 lean pulses during a second regeneration period.

Abstract: This invention provides a method of reactivating a catalyst for methacrylic acid production, which catalyst is used in production of methacrylic acid through vapor-phase oxidation of methacrolein or vapor-phase oxidative dehydrogenation of isobutyric acid, contains P and Mo, and exhibits reduced activity. The process comprises treating the catalyst, whose activity level has dropped (deteriorated catalyst), with a gas containing a nitrogen-containing heterocyclic compound (e.g., pyridine, piperidine, piperazine, quinoline).

Abstract: The present invention relates to a process for passivating pyrophorous solids by using nitrogen, carbon dioxide and oxygen under closely defined conditions to obtain a uniformly passivated solid.

Abstract: The invention relates to a method for separating and recovering rhodium from reaction products of oxosynthesis, especially reaction products containing cobalt. The invention also relates to the reuse of rhodium as a catalyst for hydroformulation and to a catalyst for hydroformulation itself. The inventive method is characterized by the following: extraction of the organic solution with an aqueous phosphate solution or a phosphate solution, water washing, oxidative treatment of the organic phase, and extraction of the organic phase with an aqueous water-soluble arylphosphine solution.

Abstract: Methods for removing soluble material from confined spaces within substrates such as containers, capsules and porous powders comprising extraction with supercritical fluids, the pressure of which is preferably modulated between an upper level and a lower level within a relatively narrow range of fluid pressure and density. The method permits enhanced extraction efficiency, catalytic reaction rates and ability to maintain catalyst activity.

Abstract: This invention provides a method of reactivating a catalyst for methacrylic acid production, which catalyst is used in production of methacrylic acid through vapor-phase oxidation of methacrolein or vapor-phase oxidative dehydrogenation of isobutyric acid, contains P and Mo, and exhibits reduced activity. The process comprises treating the catalyst, whose activity level has dropped (deteriorated catalyst), with a gas containing a nitrogen-containing heterocyclic compound (e.g., pyridine, piperidine, piperazine, quinoline).

Abstract: A ceramic honeycomb structure (1) constituted by cell walls (ribs) (2) forming a composite structure from a plurality of cells (3) being adjacent each other and a honeycomb outer wall (4) surrounding and holding the outermost peripheral cells located at the circumference of the composite structure; said composite structure satisfying the followings: the basic thickness of the cell walls (2) (the basic cell wall thickness) (Tc) is Tc≦0.12 mm, the outer wall thickness (Ts) of the honeycomb structure is Ts≧0.05 mm, and the open frontal area (P) is P≧80%, and there is a relation shown by formula: 1.10≦(Tr1˜Tr3-20)/Tc≦3.00 between the basic cell wall thickness (Tc) and each cell wall thickness (Tr1˜Tr3-20) of cells existing between an outermost peripheral cell and any cell within a first end cell from a third cell to a twentieth cell extending inwardly, taking the outermost peripheral cell as a first starting cell.

Abstract: The hydrogenation activity of a heteroatom removal catalyst, having activity for both heteroatom removal and hydrogenation, is selectively suppressed by a treatment which comprises contacting the catalyst with (i) hydrogen, (ii) a selectively deactivating agent that suppresses the catalyst's hydrogenation activity, and (iii) a protective agent, such as CO, that preserves and protects the heteroatom removal activity during the treatment. This may be achieved in a reactor while it is on-line and removing heteroatoms from a hydrocarbon feed.

Abstract: A process to regenerate metal oxide desulfurization sorbents using an oxidizing and reducing atmosphere. The sorbents may be mono- or multi-metallic in nature, and preferably comprise Cu, Ni and/or Co. If desired, secondary metals may be incorporated to increase regeneration efficiency and/or capacity. Other additives may be used to suppress hydrocarbon cracking. A sorbent containing Zn may be combined with an Fe, Co, Ni, Mo, or W catalyst or a noble metal catalyst and combinations thereof.

Abstract: A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent.

Abstract: While contacting under regeneration conditions an oxygen-containing stream with a sorbent comprising a promoter metal and zinc sulfide which has been sulfurized by contact with sulfur-containing hydrocarbons such as cracked-gasolines and diesel fuel, the oxygen partial pressure is controlled in a range of 0.5 to 2.0 psig to minimize sulfation of the sorbent.

Abstract: The present invention integrates a gasification unit into a catalyst/absorber process for removing pollutants from the combustion product of a gas turbine. A small slipstream of syngas from the gasification unit is cleaned in an acid gas removal unit to remove H2S. The syngas is then processed in a shift unit where the carbon monoxide and any COS present in the syngas are converted into hydrogen and carbon dioxide. The shifted syngas, still containing trace amounts of H2S, is then processed in a zinc oxide bed, where the trace H2S is removed. The resultant stream is hydrogen and carbon dioxide rich, making it ideal for use in regenerating the catalyst/absorber system.

Abstract: An on-line method of synthesizing or regenerating catalysts for autothermal oxidation processes, specifically, the oxidation of paraffinic hydrocarbons, for example, ethane, propane, and naphtha, to olefins, for example, ethylene and propylene. The catalyst comprises a Group 8B metal, for example, a platinum group metal and, optionally, a promoter, such as tin, antimony, or copper, on a support, preferably a monolith support. On-line synthesis or regeneration involves co-feeding a volatile Group 8B metal compound and/or a volatile promoter compound with the paraffinic hydrocarbon and oxygen into the oxidation reactor under ignition or autothermal conditions.

Abstract: Methods for removing soluble material from confined spaces within substrates such as containers, capsules and porous powders comprising extraction with supercritical fluids, the pressure of which is preferably modulated between an upper level and a lower level within a relatively narrow range of fluid pressure and density. The method permits enhanced extraction efficiency, catalytic reaction rates and ability to maintain catalyst activity.

Abstract: A fuel processing system is operative to remove substantially all of the sulfur present in a logistic fuel stock supply. The fuel stock can be gasoline, diesel fuel, or other like fuels which contain relatively high levels of organic sulfur compounds such as mercaptans, sulfides, disulfides, and the like. The system is a part of a fuel cell power plant. The fuel stock supply is fed through a reformer where the fuel is converted to a hydrogen rich fuel which contains hydrogen sulfide. The hydrogen sulfide-containg reformer exhaust is passed through a sulfur scrubber, to which is added a small quantity of air, which scrubber removes substantially all of the sulfur in the exhaust stream by means of the Claus reaction. The desulfurizing step causes sulfur to deposit on the scrubber bed, which after a period of time, will prevent further sulfur from being removed from the reformer exhaust stream.

Abstract: A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent.

Abstract: A process for regenerating a spent catalyst having coke deposits thereon in a catalyst regeneration vessel having a dense phase and a dilute phase, wherein the process comprises the steps of: (a) contacting the spent catalyst with a primary oxygen-containing gas in the dense phase, thereby combusting the coke, resulting in the formation of a combustion gas comprising nitrogen oxides and carbon monoxide which further reacts, thus reducing a majority of the nitrogen oxides to form elemental nitrogen; and (b) contacting the combustion gas with a secondary oxygen-containing gas, and typically a shield gas, at a location just above the interface between the dense phase and the dilute phase and also in the dilute phase, thereby oxidizing the remaining CO to CO2 without significant temperature rise in the dilute phase due to the after burn.