US4778665A — Abatement of NOx in exhaust gases

Claim 1

Independent Claim 122 words

A method for pretreating prior to discharge to the atmosphere an industrial exhaust gas contaminated with NO x , which method comprises: forming at a temperature of at least about 200° C. a mixture of said exhaust gas and added ammonia, said ammonia being added in an amount to satisfy approximately the stoichiometric requirement for reduction of the NO x by NH 3 ; and, contacting said mixture at 200° C. to about 600° C. and at a gas hourly space velocity effective to substantially reduce said NO x content with a commercial, spent organic conversion catalyst, said catalyst comprising a crystalline zeolite having a silica to alumina ratio of at least about 50 and a Constraint Index of 1 to 12.

Claim 2

Independent Claim 122 words

A method for pretreating prior to discharge to the atmosphere an industrial exhaust gas contaminated with NO x , which method comprises: forming at a temperature of at least about 200° C. a mixture of said exhaust gas and added ammonia, said ammonia being added in an amount to satisfy approximately the stoichiometric requirement for reduction of the NO x by NH 3 ; and, contacting said mixture at 200° C. to about 600° C. and at a gas hourly space velocity effective to substantially reduce said NO x content with a commercial, spent organic conversion catalyst, said catalyst comprising a crystalline zeolite having a silica to alumina ratio of at least about 50 and a Constraint Index of 1 to 12.

Claim 3

Dependent Claim 25 words

The method of claim 1 wherein said crystalline zeolite is selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-21, ZSM-23, ZSM-35, ZSM-38 and ZSM-48.

Claim 4

Dependent Claim 14 words

The method of claim 2 wherein said crystalline zeolite is in the hydrogen form.

Claim 5

Dependent Claim 23 words

The method of claim 2 wherein said catalyst contains from 2 ppm up to about 1 wt % of a platinum group metal.

Claim 6

Dependent Claim 21 words

The method of claim 3 wherein said catalyst contains up to about 2 wt % nickel and said zeolite is ZSM-5.

Claim 7

Dependent Claim 104 words

A process for selectively reducing oxides of nitrogen in a mixture of gases containing oxygen, reducible oxides of nitrogen, and nitrogen, which process comprises contacting in a reaction zone said mixture of gases and approximately the stoichiometric amount of added ammonia needed to reduce said reducible nitrogen oxides to nitrogen, said contacting being conducted at a temperature of 200° C. to about 600° C. with a spent commercial hydrocarbon conversion catalyst, said catalyst comprising a crystalline zeolite having a silica to alumina ratio of at least about 50 and selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-21, ZSM-23, ZSM-35, ZSM-38 and ZSM-48.

Claim 8

Dependent Claim 104 words

A process for selectively reducing oxides of nitrogen in a mixture of gases containing oxygen, reducible oxides of nitrogen, and nitrogen, which process comprises contacting in a reaction zone said mixture of gases and approximately the stoichiometric amount of added ammonia needed to reduce said reducible nitrogen oxides to nitrogen, said contacting being conducted at a temperature of 200° C. to about 600° C. with a spent commercial hydrocarbon conversion catalyst, said catalyst comprising a crystalline zeolite having a silica to alumina ratio of at least about 50 and selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-21, ZSM-23, ZSM-35, ZSM-38 and ZSM-48.

Claim 9

Dependent Claim 13 words

The method of claim 6 wherein said zeolite is in the hydrogen form.

Claim 10

Dependent Claim 23 words

The method of claim 6 wherein said mixture of gases is generated by calcining an inorganic composition that contains a metal nitrate salt.

Claim 11

Dependent Claim 29 words

The method of claim 6 wherein said mixture of gases is the exhaust from a stationary engine operating with a lean mixture of air and natural gas as fuel.

Claim 12

Dependent Claim 24 words

The method of claim 6 wherein said mixture of gases is the flue gas discharge from the regenerator of a fluid catalytic cracking unit.

Claim 13

Dependent Claim 168 words

In a process for the fluid catalytic cracking of a petroleum fraction which comprises contacting said fraction in a cracking unit with a fluid cracking catalyst whereby forming cracked products and deactivated catalyst containing a carbonaceous deposit, separating said deactivated catalyst from said cracked products, passing said deactivated catalyst to a regeneration unit where it is contacted at elevated temperature with an oxygen-containing gas whereby forming regenerated catalyst and a flue gas contaminated with NO x , discharging said flue gas, and recycling said regenerated catalyst, the improvement which comprises: adding prior to said flue gas discharging step an approximately stoichiometric amount of NH 3 to said flue gas and contacting the resultant mixture at 200° C. to 600° C. with a commercial, spent organic conversion catalyst, said catalyst comprising a crystalline zeolite having a silica to alumina ratio of at least about 50 and a Constraint Index of 1 to 12 whereby converting said NO x to an innocuous gas, and thereafter discharging said treated flue gas.

Claim 14

Dependent Claim 168 words

In a process for the fluid catalytic cracking of a petroleum fraction which comprises contacting said fraction in a cracking unit with a fluid cracking catalyst whereby forming cracked products and deactivated catalyst containing a carbonaceous deposit, separating said deactivated catalyst from said cracked products, passing said deactivated catalyst to a regeneration unit where it is contacted at elevated temperature with an oxygen-containing gas whereby forming regenerated catalyst and a flue gas contaminated with NO x , discharging said flue gas, and recycling said regenerated catalyst, the improvement which comprises: adding prior to said flue gas discharging step an approximately stoichiometric amount of NH 3 to said flue gas and contacting the resultant mixture at 200° C. to 600° C. with a commercial, spent organic conversion catalyst, said catalyst comprising a crystalline zeolite having a silica to alumina ratio of at least about 50 and a Constraint Index of 1 to 12 whereby converting said NO x to an innocuous gas, and thereafter discharging said treated flue gas.

Claim 15

Dependent Claim 19 words

The method of claim 11 wherein said contacting is effected by injection of said catalyst into said flue gas.

Claim 16

Dependent Claim 23 words

The method of claim 11 in which said contacting is effected with catalyst contained in a fixed, a fluid, or a moving bed.

Claim 17

Dependent Claim 44 words

The process of claim 1 or claim 2 or claim 3 or claim 4 or claim 6 or claim 7 or claim 8 or claim 9 or claim 10 or claim 11 or claim 12 or claim 13 wherein said crystalline zeolite is ZSM-5.

Claim 18

Independent Claim 102 words

A method for pretreating prior to discharge to the atmosphere an industrial exhaust gas contaminated with NO x , which method comprises: forming at a temperature of at least about 200° C. a mixture of said exhaust gas and added ammonia, said ammonia being added in an amount to satisfy approximately the stoichiometric requirement for reduction of the NO x by NH 3 ; and contacting said mixture at 200° C. to about 600° C. and at a gas hourly space velocity effective to substantially reduce said NO x content with a spent organic conversion catalyst comprising ZSM-5 or ZSM-11 crystalline zeolite.

Claim 19

Independent Claim 102 words

A method for pretreating prior to discharge to the atmosphere an industrial exhaust gas contaminated with NO x , which method comprises: forming at a temperature of at least about 200° C. a mixture of said exhaust gas and added ammonia, said ammonia being added in an amount to satisfy approximately the stoichiometric requirement for reduction of the NO x by NH 3 ; and contacting said mixture at 200° C. to about 600° C. and at a gas hourly space velocity effective to substantially reduce said NO x content with a spent organic conversion catalyst comprising ZSM-5 or ZSM-11 crystalline zeolite.

Claim 20

Dependent Claim 14 words

The method of claim 15 wherein said ZSM-5 zeolite is in the hydrogen form.

Claim 21

Dependent Claim 142 words

A process for pretreating prior to discharge to the atomosphere an industrial exhaust gas contaminated with an ecologically unacceptable amount of NO x , which method comprises forming at a temperature of at least about 200° C. a mixture of said exhaust gas and a variable, controlled amount of added ammonia, said amount being effective to reduce said NO x content of said discharged gas to an acceptable level, and contacting said mixture at 200° C. to at least about 600° C. with a catalyst comprising a porous crystalline siliceous solid having a pore size of at least 5 A.U., a silica to alumina ratio of at least 20, an alpha value of at least about 10 to 250, and a Dynamic Response Index (DRI) of at least 20, thereby avoiding the discharge or excessive concentrations of both NO x and ammonia.

Claim 22

Dependent Claim 142 words

A process for pretreating prior to discharge to the atomosphere an industrial exhaust gas contaminated with an ecologically unacceptable amount of NO x , which method comprises forming at a temperature of at least about 200° C. a mixture of said exhaust gas and a variable, controlled amount of added ammonia, said amount being effective to reduce said NO x content of said discharged gas to an acceptable level, and contacting said mixture at 200° C. to at least about 600° C. with a catalyst comprising a porous crystalline siliceous solid having a pore size of at least 5 A.U., a silica to alumina ratio of at least 20, an alpha value of at least about 10 to 250, and a Dynamic Response Index (DRI) of at least 20, thereby avoiding the discharge or excessive concentrations of both NO x and ammonia.

Claim 23

Dependent Claim 30 words

The process described in claim 17 wherein said porous crystalline siliceous material has a silica to alumina ratio of at least 20 and a Constraint Index of 1 to 12.

Claim 24

Dependent Claim 31 words

The process described in claim 18 wherein said porous crystalline siliceous material has the structure of ZSM-5 or ZSM-11 or ZSM-12 or ZSM-21 or ZSM-23 or ZSM-35 or ZSM-38 or ZSM-48.

Claim 25

Dependent Claim 13 words

The process of claim 18 wherein said zeolite has the structure of ZSM-5.

Claim 26

Dependent Claim 127 words

A process for controllably pretreating prior to discharge to the atmosphere an industrial exhaust gas contaminated with NO x , said process comprising: contacting, at a temperature of about 200° C. to at least about 600° C., a mixture of said exhaust gas, and added ammonia, with a solid inorganic acid catalyst comprising an acid-resistant porous crystalline siliceous solid having a silica to alumina ratio of at least 20 and that is deactivated for acid catalyzed reaction prior to said contact with said mixture, said crystalline silicate having a pore size of at least 5 Anstroms, said deactivation being effective to increase its Dynamic Rsponse Index (DRI) to at least 20 without substantially affecting the activity of said catlyst for selective catalytic reduction of NO x .

Claim 27

Dependent Claim 127 words

A process for controllably pretreating prior to discharge to the atmosphere an industrial exhaust gas contaminated with NO x , said process comprising: contacting, at a temperature of about 200° C. to at least about 600° C., a mixture of said exhaust gas, and added ammonia, with a solid inorganic acid catalyst comprising an acid-resistant porous crystalline siliceous solid having a silica to alumina ratio of at least 20 and that is deactivated for acid catalyzed reaction prior to said contact with said mixture, said crystalline silicate having a pore size of at least 5 Anstroms, said deactivation being effective to increase its Dynamic Rsponse Index (DRI) to at least 20 without substantially affecting the activity of said catlyst for selective catalytic reduction of NO x .

Claim 28

Dependent Claim 37 words

The process described in claim 21 wherein said deactivation of said catalyst for acid catalyzed reaction is effected by steaming, by the incorporation of metallic cations, by use in an acid catalyzed reaction, or by combinations thereof.

Claim 29

Dependent Claim 23 words

The process described in claim 22 wherein said metallic cations are selected from the group consisting of akali and alkaline earth metal cations.

Claim 30

Dependent Claim 20 words

The process described in claim 22 wherein said deactivation of said catalyst for acid catalyzed reaction is effected by steaming.

Claim 31

Dependent Claim 29 words

The process described in claim 21 wherein said deactivation of said catalyst for acid catalyzed reaction is effective to increase the DRI to a value of at least 33.

Claim 32

Dependent Claim 17 words

The process described in claim 21 wherein said porous crystalline siliceous solid has the structure of ZSM-5.

Claim 33

Dependent Claim 17 words

The process described in claim 22 wherein said porous crystalline siliceous solid has the structure of ZSM-5.

Claim 34

Dependent Claim 17 words

The process described in claim 23 wherein said porous crystalline siliceous solid has the structure of ZSM-5.

Claim 35

Dependent Claim 17 words

The process described in claim 24 wherein said porous crystalline siliceous solid has the structure of ZSM-5.

Claim 36

Dependent Claim 17 words

The process described in claim 25 wherein said porous crystalline siliceous solid has the structure of ZSM-5.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-10-18	1992-04-18	1992-10-18	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-10-18	1996-04-18	1996-10-18	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-10-18	2000-04-18	2000-10-18	$7700.00	Window Closed / Lapsed

Abatement of NOx in exhaust gases

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