A method for cleaning an off-gas from viscose production, essentially containing H.sub.2S and CS.sub.2, comprises passing the gas through a catalytic reactor containing a direct oxidation type catalyst, such as V.sub.2O.sub.5 on silica, to convert H.sub.2S in the gas to elemental sulfur, SO.sub.2 or mixtures thereof, either via the oxygen present in the gas or via oxygen added to the gas stream. Elemental sulfur and SO.sub.2 are removed from the effluent gas from the catalytic reactor, and the unconverted CS.sub.2 is recycled to the viscose production process.

An ignition chimney (1) for carbonaceous fuel (2) is shown and described, with a housing (3), a lower combustion chamber (4) formed in the housing (3) for easily ignitable igniter (5), with an upper combustion chamber (6) formed in the housing (3) for the carbonaceous fuel (2), wherein, in the ready-for-operation state, the upper combustion chamber (6) is arranged above the lower combustion chamber (4), and the lower combustion chamber (4) and the upper combustion chamber (6) are separated from one another by a gas-permeable separator (7), the upper side (8) of the separator (7), which faces the upper combustion chamber (6), forming a receptacle for the fuel (2), the separator (7) being designed such that the igniter exhaust gases (9) produced in the ignited state of the igniter (5) pass through the separator (7) and impinge on the fuel (2) resting on the separator (7).

The risk of carbon monoxide poisoning by exhaust gases during combustion of the (carbonaceous) fuel is considerably reduced in the ignition chimney in that a catalyst (11) for catalyzing the oxidation of carbon monoxide to carbon dioxide with oxygen is arranged above the receptacle for the fuel (2) in such a way, that the fuel exhaust gases (12) produced in the ignited state of the fuel (2) are at least partially conducted to the catalyst (11) or through the catalyst (11) and at least part of the carbon monoxide present in the fuel exhaust gases (12) is oxidized to carbon dioxide.

Provided is a combustion system in which a catalyst having superior denitration efficiency at a low temperature compared with those used in the conventional techniques is used in a selective catalytic reduction reaction using ammonia as a reducing agent. A combustion system equipped with: a denitration device which is arranged in the exhaust passage and can remove a nitrogen oxide from the exhaust gas with a denitration catalyst. In the combustion system, the denitration device is arranged on the downstream side of the dust collection device in the exhaust passage, and the denitration catalyst is one which contains vanadium oxide as the main component and in which the content of a second metal in terms of oxide content is 1 to 40 wt % inclusive, wherein the second metal comprises at least one metal element selected from the group consisting of Co, W, Mo, Nb, Ce, Sn, Ni, Fe, Cu, Zn and Mn.

Provided through the present disclosure is a method for reducing nitrogen dioxide in exhaust gas of a stationary source by using selective catalytic reduction (SCR) without injection of a reducing agent, the method comprising the steps of: (a) providing exhaust gas generated in the stationary source wherein the exhaust gas includes at least one of CO, H.sub.2, and hydrocarbon; (b) contacting the exhaust gas with a catalyst to reduce nitrogen dioxide in the exhaust gas; and (c) discharging into air the exhaust gas that has undergone step (b).

A process for preparing a zeolitic material having framework type AEI and having a framework structure which comprises a tetravalent element Y, a trivalent element X, and oxygen, said process comprising (i) providing a zeolitic material having framework type CHA and having a framework structure comprising the tetravalent element Y, the trivalent element X, and oxygen; (ii) preparing a synthesis mixture comprising the zeolitic material provided in (i), water, a source of the tetravalent element Y other than the zeolitic material provided in (i), and an AEI framework structure directing agent; (ili) subjecting the synthesis mixture prepared in (ii) to hydrothermal synthesis conditions comprising heating the synthesis mixture to a temperature in the range of from 100 to 200° C. and keeping the synthesis mixture at a temperature in this range under autogenous pressure, obtaining the zeolitic material having framework type AEI; wherein Y is one or more of Si, Ge, Sn, Ti, Zr; wherein X is one or more of Al, B, Ga, In; wherein in the framework structure of the zeolitic material provided in (i), the molar ratio Y:X, calculated as YO2: X2O3, is at most 20:1 and, wherein; the process further comprises supporting a metal M selected from the transition metals of groups 7 to 12 of the periodic system of elements.

Provided is a catalyst which, when used in a selective catalytic reduction reaction in which ammonia serves as the reducing agent, further improves denitration efficiency at low temperatures compared to the prior art.

The denitration catalyst comprises vanadium oxide as a main component, and has a content of a second metal, in teams of oxide, of 1-40 wt %. The second metal is at least one type of metal element selected from the group consisting of Co, W, Mo, Nb, Ce, Sn, Ni, Fe, Cu, Zn, and Mn.

A mask structure with an externally connected filtering device includes a mask body, a unidirectional air seat valve, at least one connecting tube and a filtering device. The mask body is made of an air-impermeable material, can be provided with the unidirectional air seal valve thereon and connected with the filtering device through the connecting tube, so that the mask structure can filter and purify ambient air by the filtering device, and deliver the filtered air to the inner side of the mask body through the connecting tube for a user to inhale. The exhaled air by the user can be expelled through the unidirectional air seal valve to the outer side of the mask body.

A system comprising a housing; a filter retained within the housing; optionally, an activation mechanism configured to, during operation, activate the filter; and a flow controller configured to urge fluid through the filter.

Organic sulfur compounds contained in refinery off gas streams having either high or low concentrations of olefins are converted to hydrogen sulfides which can be then be removed using conventional amine treating systems. The process uses a catalytic reactor with or without a hydrotreater depending on the olefin concentration of the off gas stream. The catalytic reactor operates in a hydrogenation mode or an oxidation mode to convert a majority of organic sulfur compounds into hydrogen sulfides.

A pillar-shaped honeycomb structure including an outer peripheral side wall, a plurality of first cells provided on an inner peripheral side of the outer peripheral side wall, the first cells extending from a first end surface to a second end surface, each opening on the first end surface and having a sealing portion with an average void ratio of 4% or less on the second end surface, and a plurality of second cells provided on the inner peripheral side of the outer peripheral side wall, the second cells extending from the first end surface to the second end surface, each having a sealing portion with an average void ratio of 4% or less on the first end surface and opening on the second end surface, the first cells and the second cells being alternately arranged adjacent to each other with a partition wall interposed therebetween.