Process for commissioning an exhaust particulate filter

A process for commissioning a particulate filter for the exhaust system of a device, the device being powered in whole or in part by an internal combustion engine fuelled by a liquid hydrocarbonaceous fuel untreated with lubricating oil, the process comprising:

• (i) passing a gas stream through an uncarbonised new, or decarbonised reconditioned, particulate filter comprising a ceramic monolith with channels, which in turn comprises end-plugs;
• (ii) releasing into the gas stream upstream of the particulate filter a flow of metal oxide particles in a single period of release sufficient to deposit metal oxide particles onto the uncarbonised or decarbonised surfaces of the end-plugs of the channels of the monolithic filter exposed to the gas stream;
• and
• (iii) consigning the particulate filter to operate on the exhaust gas emitted from the internal combustion engine of the device in service,
• wherein the gas stream of the commissioning step (i) is the exhaust gas stream emitted from the internal combustion engine of the device when first operated after installation of the particulate filter, wherein the metal oxide particles used in the commissioning step (ii) are released into the exhaust gas stream upstream of the particulate filter by addition of a fuel additive to a single quantity of engine fuel which, upon combustion of the fuel, releases metal oxide particles into the exhaust gas stream emitted from the combustion chamber,
• wherein the fuel additive consists of iron oxide colloidally dispersed by one or more organic compounds in a hydrocarbonaceous diluent to disperse the iron oxide in the fuel and does not contain any lubricating oil or other, heavier petroleum fraction or additives originating therefrom, and
• wherein the internal combustion engine is fueled by a liquid hydrocarbonaceous fuel untreated with lubricating oil, such that the process results in the commissioned filter having a mean filtration efficiency increase of at least 25% and simultaneously an increase in a mean pressure difference across the commissioned filter of less than 25%, relative to a pre-commissioned filter, when the internal combustion engine is operated at 5,500 rpm and 300 Nm torque.