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 and germanium, and has a content of heteroatom T-atoms of ≤about 0.20 mol %, wherein the germanium is present in an amount of from 15 to 20 mol %. The present invention further relates to a catalyst article and 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 and germanium, and has a content of heteroatom T-atoms of ≤0.20 mol %,
wherein the germanium is present in an amount of from 15 to 20 mol %.
2 . The catalytic material according to claim 1 , wherein the heteroatom T-atom is selected from a group consisting of aluminium (Al), boron (B), gallium (Ga), titanium (Ti), zinc (Zn), iron (Fe), vanadium (V) and combinations of any two or more thereof.
3 . The catalytic material according to claim 1 , wherein the framework consists essentially of silicon, oxygen, germanium and heteroatom T-atoms.
4 . The catalytic material according to claim 1 , wherein the molecular sieve is a zeolite.
5 . The catalytic material according to claim 4 , wherein the zeolite is selected from the group consisting of BEA, CDO, CON, MEL, MWW, MFI, and FAU.
6 . The catalytic material according to claim 4 , wherein the zeolite is MFI.
7 . The catalytic material according to claim 1 , wherein the platinum group metal (PGM) is present in a total amount of 0.01 to 30 wt %.
8 . The catalytic material according to claim 7 , wherein the platinum group metal (PGM) is selected from a group consisting of palladium (Pd), and a combination of platinum (Pt) and palladium (Pd).
9 . The catalytic material according claim 8 , wherein the palladium is present in an amount of 0.1 to 20 wt %.
10 . The catalytic material according to claim 1 , wherein the molecular sieve has a silica to alumina ratio (SAR) of ≥1200.
11 . The catalytic material according to claim 1 , wherein the molecular sieve comprises at least 0.010 mmol/g of silanol groups.
12 . A catalyst article comprising the catalytic material of claim 1 dispersed in a substrate.
13 . A catalyst article comprising the catalytic material of claim 1 on a substrate.
14 . The catalyst article according to claim 13 wherein the catalytic material is provided as a washcoat on the substrate.
15 . The catalyst article of claim 14 , wherein the washcoat has a washcoat loading from 1 to 50 g/ft 3 .
16 . The catalyst article according to claim 13 , wherein the substrate is a flow-through substrate or a filtering substrate.
17 . 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 natural gas combustion engine and a catalyst article according to claim 10 arranged to receive and treat the exhaust gas.