CATALYTIC MATERIAL FOR TREATING AN EXHAUST GAS PRODUCED BY A NATURAL GAS ENGINE
The present invention relates to a catalytic material for treating an exhaust gas produced by a natural gas engine, which catalytic material comprises a molecular sieve and a platinum group metal (PGM) supported on the molecular sieve, wherein the molecular sieve has a framework comprising silicon, oxygen, titanium and optionally germanium, and has a content of non-titanium heteroatom T-atoms of ≤ about 0.20 mol %, wherein the titanium is present in an amount of from 1 to 3 mol %. The present invention further relates to a catalyst article and to a compressed natural gas combustion and exhaust system.
1 . A catalytic material for treating an exhaust gas produced by a natural gas engine, which catalytic material comprises a molecular sieve and a platinum group metal (PGM) supported on the molecular sieve,
wherein the molecular sieve has a framework comprising silicon, oxygen, titanium and optionally germanium, and has a content of non-titanium heteroatom T-atoms of ≤ about 0.20 mol %,
wherein the titanium is present in an amount of from 1 to 3 mol %.
2 . A catalytic material according to claim 1 , wherein the heteroatom T-atom is selected from the group consisting of aluminium (Al), boron (B), gallium (Ga), zinc (Zn), iron (Fe), vanadium (V) and combinations of any two or more thereof.
3 . A catalytic material according to claim 1 , wherein the framework consists essentially of silicon, oxygen, titanium and heteroatom T-atoms.
4 . A catalytic material according to claim 1 , wherein the molecular sieve is a zeolite.
5 . A catalytic material according to claim 1 , wherein the total amount of the platinum group metal (PGM) is from 0.01 to 30 wt %.
6 . A catalytic material according to claim 5 , wherein the platinum group metal (PGM) is selected from the group consisting of palladium (Pd), and a combination of platinum (Pt) and palladium (Pd).
7 . A catalytic material according claim 6 , wherein the total amount of palladium is 0.1 to 20 wt %.
8 . A catalytic material according to claim 1 , wherein the molecular sieve has a SAR of ≥1200.
9 . A catalytic material according to claim 1 , wherein the molecular sieve comprises at least 0.010 mmol/g of silanol groups.
10 . A catalyst article comprising the catalytic material of claim 1 on a substrate.
11 . A catalyst article according to claim 10 wherein the catalytic material is provided as a washcoat on the substrate.
12 . The catalyst article of claim 11 , wherein the washcoat loading is from 1 to 50 g/ft 3 .
13 . A catalyst article comprising the catalytic material of claim 1 dispersed in a substrate.
14 . A catalyst article according to claim 10 , wherein the substrate is a flow-through substrate or a filtering substrate.
15 . A compressed natural gas combustion and exhaust system comprising:
(i) a natural gas combustion engine; and
(ii) an exhaust treatment system comprising an intake for receiving an exhaust gas from the combustion engine and a catalyst article according to claim 10 arranged to receive and treat the exhaust gas.