The present invention provide a method for purifying exhaust gas in which nitrogen oxides (NOx) gas is removed from a combustion exhaust gas. The method for purifying exhaust gas according to the invention is characterized in that water vapor is further added to raw exhaust gas to be processed to increase the water vapor concentration in the exhaust gas and the resulting moisture-adjusted exhaust gas is introduced into a denitration catalyst layer. The water vapor concentration in the moisture-adjusted exhaust gas is preferably 22.0% by volume or less in the total of the water vapor originally contained in the raw exhaust gas and the added water vapor.

Disclosed herein are methods, systems, and compositions for providing catalysts for tail gas clean up in sulfur recovery operations. Aspects of the disclosure involve obtaining catalyst that was used in a first process, which is not a tailgas treating process and then using the so-obtained catalyst in a tailgas treating process. For example, the catalyst may originally be a hydroprocessing catalyst. A beneficial aspect of the disclosed methods and systems is that the re-use of spent hydroprocessing catalyst reduces hazardous waste generation by operators from spent catalyst disposal. Ultimately, this helps reduce the environmental impact of the catalyst life cycle. The disclosed methods and systems also provide an economically attractive source of high-performance catalyst for tailgas treatment, which benefits the spent catalyst generator, the catalyst provider, and the catalyst consumer.

A structured monolithic catalyst has a structured monolithic carrier and a coating of active components. The coating of active components comprises active metal components and a substrate. The active metal components conclude a first metal element, a second metal element, a third metal element and a fourth metal element. The first metal element includes Fe and Co; the second metal element is at least one selected from the group consisting of the metal elements of the Group IA and/or IIA; the third metal element is at least one selected from the group consisting of the non-noble metal elements of the Groups IB to VIIB; and the fourth metal element is at least one selected from the group consisting of the noble metal elements.

A catalyst fibrous structure having a catalyst metal carried on a fibrous structure, wherein (a) a Log differential micropore volume distribution curve thereof obtained by measurement using a mercury intrusion technique has a peak having a maximum micropore diameter in the range of from 0.1 μm to 100 μm; (b) a Log differential micropore volume at the peak is 0.5 mL/g or more; and (c) an amount of a catalyst metal compound and a binder carried per unit volume is 0.05 g/mL or more. A production method for producing a catalyst fibrous structure having: (1) mixing a catalyst metal compound or a catalyst precursor, and an inorganic binder and a solvent; (2) grinding the mixture to obtain a coating material of the catalyst metal compound or the catalyst precursor having a median particle diameter of 2 μm or less and a viscosity of from 10 mPa.Math.s to 200 mPa.Math.s; (3) impregnating a fibrous structure with the coating material to fill up voids of the fibrous structure with the coating material of the catalyst metal compound or the catalyst precursor; (4) heating and drying the fibrous structure, directly as it is, at a temperature not lower than the boiling point of the solvent; and (5) heating and calcination the dried fibrous structure at a temperature not lower than the dehydration temperature of the inorganic binder to obtain a catalyst fibrous structure.

A multi-scaled oxygen storage material wherein cobalt element is complexed with a size of an atom or hundreds of nanometers or smaller in a ceria-zirconia solid solution and a method for preparing the same are provided.

Specifically, The multi-scaled oxygen storage material contains a ceria-zirconia solid solution, a cobalt dopping contained in the solid solution in the form of an atom and a cobalt-based nanocluster dispersed in the solid solution as cobalt oxide and exhibits a microstructure distinguished from that of the existing ceria-zirconia (CZO)-based oxygen storage material as well as remarkably improved oxygen storage and release ability, and the method for preparing the same is provided.

Centralizing the handling and manipulating of vaporization medium to a single subsystem that supplies multiple ammonia vaporizers allows for efficient and effective production of a corresponding vaporized ammonia stream containing a controlled quantity of ammonia. These vaporized ammonia streams can then be used in conjunction with ammonia-consuming devices to reduce NOx in NOx-containing exhaust streams from multiple furnaces.

The present invention provides a catalyst for the decomposition of nitrous oxide, said catalyst comprising oxides of cobalt, zinc and aluminum and an alkali metal promoter.

In an exhaust gas purification system provided with a denitration catalyst layer, a reducing agent oxidation catalyst layer is installed together; a reducing agent and air are supplied into the reducing agent oxidation catalyst layer at the time of catalyst regeneration of the denitration catalyst layer; a high-temperature oxidation reaction gas is produced by a reaction heat generated by an oxidation reaction of the reducing agent and the air in this reducing agent oxidation catalyst layer; and this high-temperature oxidation reaction gas is introduced into the denitration catalyst layer to heat the denitration catalyst, thereby recovering a denitration performance of the catalyst.

A honeycomb structure includes: a honeycomb structure body including a plurality of cells; and a plugging portion to alternately plug open end parts of the plurality of cells on one side as an inflow side of the exhaust gas and open end parts on the other side as an outflow side of the exhaust gas. The partition wall is loaded, on the side of the outflow cells, with an oxidation catalyst made of a transition metal oxide to oxidize NO gas or an oxidation catalyst made of a transition metal oxide loaded at CeO.sub.2 to oxidize NO gas. The partition wall has porosity of 70% or less, the oxidation catalyst has a particle diameter of more than 1 μm and less than 50.0 μm, and the loading amount of the oxidation catalyst is 5.0 g/L or more and 50 g/L or less.

The present invention is related to a catalyst supported for the selective oxidation of sulphur compounds of the tail gas from the Claus process or streams with an equivalent composition to elemental sulphur or sulphur dioxide (SO.sub.2). It is also the object of the present invention, a process for the preparation of a catalyst of this type, as well as the process of selective oxidation of sulphur compounds to elemental sulphur using the catalyst of the invention, as well as the process of catalytic incineration of the tail gas from the Claus process using the catalyst of the present invention.