Abstract: Provided is a hot-top type continuous casting machine for stably producing hot metal hollow billets having a high quality, which comprises: (a) a molten metal holding part fed therein with molten metal; (b) a ring mold arranged being connected to the molten metal holding part; and (c) a core inserted in the hollow mold from thereabove, and composed of a low heat-conductive upper core and a high heat-conductive lower core to be cooled by coolant circulating therethrough.

Abstract: A reduction purification method of a nitrogen oxide-containing exhaust gas by contacting said nitrogen oxide-containing exhaust gas with a catalyst in an oxidative atmosphere in which an excess amount of oxygen is present and in the presence of a least one reducing agent selected from the group consisting of a hydrocarbon and an oxygen-containing organic compound, wherein said catalyst comprises an alumina having supported thereon (a) tin and (b) at least one selected from the group consisting of ruthenium, palladium, rhodium and indium.

Abstract: A reduction purification method of a nitrogen oxide-containing exhaust gas by contacting said nitrogen oxide-containing exhaust gas with a catalyst in an oxidative atmosphere in which an excess amount of oxygen is present and in the presence of at least one reducing agent selected from the group consisting of a hydrocarbon and an oxygen-containing organic compound, wherein said catalyst comprises an alumina having supported thereon (a) tin and (b) at least one selected from the group consisting of ruthenium, palladium, rhodium and indium.

Abstract: A process for removing nitrogen oxide from exhaust is disclosed, comprising contacting exhaust containing nitrogen oxide with an alumina catalyst which contains not more than 0.5% by weight of an alkali metal and/or an alkaline earth metal and has a total pore volume of from 0.48 to 1.2 cm.sup.3 .multidot.g.sup.-1 with 0.26 to 0.6 cm.sup.3 .multidot.g.sup.-1 of the total pore volume being formed of pores of not greater than 80 .ANG. or has a volume of pores formed of pores of not greater than 60 .ANG. of from 0.06 to 0.2 cm.sup.3 .multidot.g.sup.-l and which may have supported thereon tin in an oxidative atmosphere containing excess oxygen in the presence of a hydrocarbon or an oxygen-containing organic compound.

Abstract: A catalyst for catalytic reduction of nitrogen oxides using a hydrocarbon and/or a oxygen-containing organic compound as a reducing agent is disclosed, which comprises a cerium oxide supported on a solid acid carrier.Also, a catalyst for catalytic reduction of nitrogen oxides using a hydrocarbon and/or an oxygen-containing organic compound as a reducing agent is disclosed, which comprises:(a) at least one element selected from the elements of Group Ib, Group IIa, Group IIb, Group IIIa, Group IIIb, Group IVa, Group IVb, Group Va, Group VIa, Group VIIa, and Group VIII in the Periodic Table (hereinafter referred to as the elements belonging to group (a)); and(b) a cerium oxide, supported on a solid acid carrier.

Abstract: A catalyst for catalytic reduction of nitrogen oxide using at least one reducing agent selected from the group consisting of a hydrocarbon and an oxygen-containing organic compound is described, which includes an oxide represented by formula (V):A.sup.5.sub.x B.sup.3.sub.3-x C.sup.4.sub.3 O.sub.7 (V)wherein A.sup.5 represents at least one element selected from the group consisting of La, Y, Ce, Pr, Nd, Sm, Eu, and Gd; B.sup.3 represents at least one element selected from the group consisting of Ba, Sr, Ca, Mg, Pb, Zn, and Ag; C.sup.4 represents at least one element selected from the group consisting of Mn, Co, Fe, Ni, Cr, Cu, V, Mo, W, Ti, Zr, Nb, Pd, Rh, Ru, and Pt; and x is a number of from 0 to 1, supported on a solid acid carrier.