Ineos said it had selected the location for a new ethane tank it plans to build at Grangemouth, with imports starting as early as 2016 after a £150 million investment to an import terminal project.
The move will supplement declining North Sea supp-lies, said Ineos, which threatened to close the petro- chemical site in October after a dispute with the Unite union.
The company decided to keep the site open after workers accepted changes to pay, pensions and terms and conditions.
However, the Unite union has warned that up to 200 workers at Grangemouth are set to lose their jobs under cost-cutting moves. The union said five plants at the huge site will close, while shift payments will be cut by £2500 a year and new employees will receive lower wages.
Unite's Scottish secretary Pat Rafferty said: "We shouldn't forget that this new facility has only been made possible because of the welcome investment by Scottish and UK taxpayers and the sacrifice of the workforce.
"Ineos needs to come clean over job losses."
Calum MacLean, chairman of Ineos Petrochemicals UK, said: "This investment is absolutely critical.
"We are delighted to report that Ineos are making good progress on the project that will give Grangemouth a sustainable future."