A chamber configured to confine a chemical reaction producing liquid biodiesel fuel from a liquid reactant mixture containing oil. The chamber comprises a membrane wall having a pore size capable of allowing flow of liquid biodiesel fuel through the membrane wall and retaining unreacted oil within the chamber. The membrane wall is further layered with one or more heterogeneous coatings of solid particles operable to catalyze the chemical reaction producing liquid biodiesel fuel from the liquid reactant mixture. Most of solid particles have a dimension larger than the pore size of the membrane wall so that they do not enter and clog the pores. Optionally, there are two coatings comprising a basic catalyst for a transesterification reaction and an acidic catalyst for an esterification reaction.