While in France, Norbert Rillieux started researching ways to improve the process of sugar refining. Meanwhile, back in Louisiana, Norbert’s brother, Edmond, a builder, along with their cousin, Norbert Soulie, an architect, began working with Edmund Forstall to build a new Louisiana Sugar Refinery. In 1833, Forstall, having heard about Rillieux’s research into sugar refining, offered him the position of Head Engineer at the not-yet-completed sugar refinery. Rillieux accepted the offer and returned to Louisiana to take up his new position. However, the sugar refinery was never completed due to disagreements between the principals, mainly Edmond Rillieux, his father, Vincent Rillieux, and Edmund Forstall. These disagreements created long-term resentments between the Rillieux family and Edmund Forstall.

In 1881, at the age of 75, Rillieux made one last foray into sugar evaporation when he adapted his multiple effect evaporation system to extract sugar from sugar beets. The process for which he filed patent was far more fuel-efficient than that currently in use in the beet sugar factories in France. Prior to Rillieux’s invention, two engineers developed a vacuum pan and electric coils to improve the process of making sugar, but this was unsuccessful due to the use of steam at wrong locations in the machine. Rillieux’s process fixed the errors in the previous process, but Rillieux lost the rights to the patent he had filed.

Norbert Rillieux died on October 8, 1894, at the age of 88. He is buried in Père Lachaise Cemetery in Paris. His wife, Emily Cuckow, died in 1912 and is buried beside him.