Process for selective reduction of oxides of nitrogen

Claim 2

A PROCESS FOR SELECTIVELY REDUCING OXIDES OF NITROGEN TO NITROGEN IN A MIXTURE OF GASES CONTAINING FROM A TRACE TO 10 PERCENT OXYGEN, FROM A TRACE TO 2 PERCENT NITRIC OXIDE, FROM A TRACE TO 2 PERCENT NITROGEN DIOXIDE AND THE REMAINDER AN INERT GAS, WHICH COMPRISES CONTACTING IN A REACTION ZONE SAID MIXTURE OF GASES AND AN APPROXIMATELY STOICHIOMETRIC AMOUNT OF AMMONIA BASED ON MOLES OF NITROGEN OXIDES PRESENT AT A SPACE VELOCITY OFLESS THAN 60,000 AND A TEMPERATURE WITH THE RANGE OF 200*C TO 300*C IN THE PRESENCE OF A CATALYST CONSISTING OF AN ACID RESISTANT ALUMINOSILICATE MOLECULAR SIEVE COMPOSITION HAVING A SURFACE AREA OF AT LEAST 350 M2/G AND SUBSTANTIALLY UNIFORM INTERCRYSTALLINE PORES WITH EFFECTIVE DIAMETERS OF AT LEAST 6 A., WHEREBY SELECTIVE REDUCTION OF THE OXIDES OF NITROGEN TO NITROGEN IS EFFECTED.

Claim 3

A process for selectively reducing oxides of nitrogen to nitrogen in a mixture of gases containing from a trace to 10 percent oxygen, from a trace to 2 percent nitric oxide, from a trace to 2 percent nitrogen dioxide and the remainder an inert gas, which comprises contacting in a reaction zone said mixture of gases and an approximately stoichiometric amount of ammonia based on moles of nitrogen oxides present at a space velocity of 3,000 to 30,000 and a temperature within the range of 200*C to 300*C in the presence of a catalyst consisting of an acid resistant aluminosilicate molecular sieve composition having a theoretical silica to alumina ratio of 10, a surface area of at least 350 m2/g and substantially uniform intercrystalline pores with effective diameters of 8 to 9 A., whereby selective reduction of the oxides of nitrogen to nitrogen is effected.

Claim 4

A process for selectively reducing oxides of nitrogen to nitrogen in a mixture of gases containing from a trace to 10 percent oxygen, from a trace to 2 percent nitric oxide, from a trace to 2 percent nitrogen dioxide and the remainder an inert gas, which comprises contacting in a reaction zone said mixture of gases and an approximately stoichiometric amount of ammonia based on moles of nitrogen oxides present at a space velocity of 3,000 to 30,000 and a temperature within the range of 200*C to 300*C in the presence of a catalyst consisting of an acid resistant aluminosilicate molecular sieve composition having a theoretical silica to alumina ratio of 10, a surface area of at least 350 m2/g and substantially uniform intercrystalline pores with effective diameters of 8 to 9 A., whereby selective reduction of the oxides of nitrogen to nitrogen is effected.