An exhaust gas cleaner constituted by a first catalyst comprising a first porous inorganic oxide supporting an Ag component, a W component and a Pt component and optionally a second catalyst comprising a second porous inorganic oxide supporting a Pt component alone or in combination with a W component. The Ag component may include Ag and compounds thereof, the Pt component of the first and second catalysts may include Pt, Pd, Ru, Rh, Ir and Au, and the W component of the first and second catalysts may include W, V, Mn, Mo, Nb and Ta. The W component effectively catalyze the reduction of nitrogen oxides by ammonia to enhance the removal efficiency of the exhaust gas cleaner.

Exhaust gas cleaner and method for cleaning exhaust gas

Nitrogen oxides are removed from an exhaust gas containing nitrogen oxides and oxygen in an amount larger than its stoichiometric amount relative to unburned components in the exhaust gas, by (i) disposing an exhaust gas cleaner in a flow path of the exhaust gas, the exhaust gas cleaner comprising 0.2-15 weight % (on a metal basis) of fine silver or silver oxides having an average diameter of 10-1,000 nm and supported on a porous inorganic oxide; (ii) introducing hydrocarbons and/or oxygen-containing organic compounds into the exhaust gas on the upstream side of the exhaust gas cleaner; and (iii) bringing the exhaust gas into contact with the exhaust gas cleaner at a temperature of 200°-600° C., thereby causing a reaction of nitrogen oxides with the hydrocarbons and/or oxygen-containing organic compounds.

Exhaust gas cleaner and method for removing nitrogen oxides

The present invention relates to a process for preparing a hydroprocessing catalyst comprising the steps of subjecting a spent hydroprocessing catalyst comprising carbonaceous and sulphurous deposits to a thermal treatment to remove at least part of said deposits, grinding the thus obtained spent catalyst, mixing the ground hydroprocessing catalyst with at least one additive, and shaping the mixture of additive and ground hydroprocessing catalyst to form particles of a new hydroprocessing catalyst, with the spent hydroprocessing catalyst being subjected to a high-temperature calcination step carried out at a temperature in the range of 550-1000° C. for a period sufficient to increase the MPD of the spent catalyst by at least 0.5 nm. The process according to the invention is particularly suitable for preparing ebullated bed catalysts from spent hydroprocessing catalysts.

Process for preparing a large pore hydroprocessing catalyst

Nitrogen oxides are efficiently removed from an exhaust gas containing nitrogen oxides and an excess amount of oxygen, by (i) disposing an exhaust gas cleaner in a flow path of the exhaust gas, the exhaust gas cleaner comprising a first catalyst comprising 0.2-15 weight % (on a metal basis) of at least one silver salt selected from the group consisting of silver halides, silver sulfate and silver phosphate supported on a porous inorganic oxide on an inlet side and a second catalyst comprising (a) 0.2-15 weight % (on a metal basis) of at least one silver salt selected from the group consisting of silver halides, silver sulfate and silver phosphate and (b) up to 2 weight % (on a metal basis) of copper or copper oxide supported on a porous inorganic oxide on an outlet side; (ii) introducing at least one reducing agent selected from hydrocarbons and oxygen-containing organic compounds into the exhaust gas on an upstream side of the exhaust gas cleaner; and (iii) bringing the exhaust gas into contact with the exhaust gas cleaner at a temperature of 200°-600° C.

Exhaust gas cleaner and method for cleaning same

A method for regeneration of a molybdenum-containing oxide fluidized bed catalyst which comprises impregnating a fluidized catalyst of a metal oxide containing molybdenum, bismuth and iron which has been deteriorated by being used for a reaction in production of acrylonitrile by ammoxidation of propylene, with a solution of a molybdenum compound and a solution of at least one compound containing at least one element selected from the group consisting of iron, chromium, lanthanum and cerium which are prepared separately or with a previously prepared mixed solution of the above compounds, drying the resulting catalyst and, then, firing the catalyst at a temperature of 500-700° C.

Method for regenerating molybdenum-containing oxide fluidized-bed catalyst

A process for regenerating deactivated metal oxide catalysts comprising at least one of the elements antimony, iron, bismuth, molybdenum, vanadium, tungsten and/or uranium and a peptizable carrier, comprises the steps of: a) grinding the metal oxide catalyst in the presence of water to a particle size of from 10 nm to 10 μm, b) heating the aqueous suspension of the metal oxide catalyst of stage a) to 30-100° C. and adding an acid which peptizes the carrier, c) spray drying the acidic suspension of the metal oxide catalyst, d) heating the fluidizable metal oxide catalyst particles of stage c) to 500°-850° C.

Regeneration of metal oxide catalysts

In a catalyst for the decomposition of nitrous oxide, pure or in gaseous mixtures, metallic silver is applied to an alumina support having a BET surface area of 5 to 25 m /g.

Process for catalytic decomposition of nitrous oxide, pure or in gaseous mixtures

Process for regenerating metal oxide catalysts having reduced activity, which contain at least one of the elements antimony, iron, bismuth, molybdenum, vanadium, tungsten and/or uranium and a peptisable support, which process comprises the following steps: a) grinding the metal oxide catalyst, water being used at the same time, to a particle size of from 10 nm to 10 mu m, b) heating the aqueous suspension of the metal oxide catalyst from step a) to a temperature of from 30 to 100 DEG C and adding an acid which peptises the catalyst carrier, c) spray-drying the acidic suspension of the metal oxide catalyst, d) heating the fluidisable metal oxide catalyst particles from step c) to a temperature of from 500 to 850 DEG C. t

Herzog Klaus Dr

Papers

Regeneration of metal oxide catalysts

Process for catalytic decomposition of nitrous oxide, pure or in gaseous mixtures

Process for regenerating metal oxide containing catalysts