Cannabinoids extraction and conversion

A method for extracting cannabidiol from hemp and converting said cannabidiol to tetrahydrocannabinol that comprises the steps of:

• a) Providing 2 vessels, vessel 1 and vessel 2, wherein vessel 2 is connected to vessel 1, and a separator vessel connected to vessel 2;
• b) Milling dried hemp biomass in order to obtain a product having a bulk density of at least 0.2 g/cm3;
• c) Decarboxylating the dried biomass of step b);
• d) Filling vessel 1 with the milled and decarboxylated biomass of step c);
• e) Filling vessel 2 with silica gel, selected from hydrated nanoporous silicon dioxide;
• f) In vessel 1, extracting a product comprising predominantly cannabidiol with other minor cannabinoids from the milled and decarboxylated biomass by injecting subcritical liquid carbon dioxide at a pressure of at least 6500 kPa (65 bars) and a temperature of less than 31° C., with a mass ratio carbon dioxide to biomass of at least 10 kg CO2/kg biomass and for a period of time ranging between 30 minutes and 8 hours;
• g) Continuously flowing the extraction product of step f) into vessel 2 filled with silica gel wherein said vessel 2 is submitted to the same flow of subcritical liquid carbon dioxide as vessel 1, that is, the same mass ratio carbon dioxide to biomass, the same temperature, the same pressure and the same period of time as in vessel 1;
• h) Retrieving and separating terpenes and waxes in the separator vessel connected to vessel 2;
• i) In vessel 2, converting cannabidiol to tetrahydrocannabinol by submitting said vessel 2 to a flow of supercritical carbon dioxide at a mass ratio carbon dioxide to biomass of at least 10 kg CO2/kg biomass and for a period of time ranging between 30 minutes and 8 hours;
• and
• j) Sequentially recovering all products in the separator vessel said products comprising in order of recovery CBD, Δ9-THC and Δ8-THC, and other minor cannabinoids.