Repurposing fluidized catalytic cracking (FCC) systems to generate renewable fuel intermediate compositions

A method of repurposing a fluid catalytic cracking (FCC) system originally designed for cracking vacuum gas oil (VGO), the method comprising:

• generating a first mixture of a renewable lipid feedstock, steam, and a particulate catalyst, wherein the particulate catalyst comprises a metal oxide catalyst on an oxide support;
• flowing the first mixture through a riser for a sufficient time for the particulate catalyst to promote reactions of the renewable lipid feedstock to generate a second mixture comprising (i) catalyst particles to which acidic reaction intermediates are sorbed and (ii) a vapor-phase intermediate composition which is essentially acid free, wherein the reaction within the riser is performed at a temperature of about 400° C. to about 700° C.;
• flowing the second mixture from the riser into a reactor/stripper which is partially filled with more of the particulate catalyst;
• within the reactor/stripper:
• contacting the second mixture with the particulate catalyst for a sufficient residence time for the particulate catalyst to promote reactions, to substantial completeness, of the acidic reaction intermediates in the second mixture to generate additional vapor-phase intermediate composition which is essentially acid free;
• and
• disengaging the vapor-phase intermediate composition from the particulate catalyst;
• collecting the disengaged vapor-phase intermediate composition;
• regenerating in a regenerator some or all of the used particulate catalyst from the reactor/stripper;
• and
• recycling the regenerated particulate catalyst into contact with additional renewable lipid feedstock in the riser,
• wherein the renewable lipid feedstock and the steam are substantially the only inputs to the FCC system for reactions which are catalyzed by the particulate catalyst, and wherein the renewable lipid feedstock is substantially the only feedstock input to the FCC system.