Production of cannabidiol from hemp using subcritical liquid carbon dioxide

1 . A method for extracting cannabidiol from hemp that comprises the steps of:

a) Providing an apparatus comprising 2 separate vessels;

b) Milling dried hemp biomass in order to obtain a product having a bulk density of at least 0.2 g/cm 3 ;

c) Decarboxylating the dried biomass of step b);

d) Filling the first vessel with the milled and decarboxylated biomass of step c);

e) Extracting a product comprising cannabidiol, tetrahydro-cannabinol Δ9-THC and Δ8-THC and other cannabinoids from the milled and decarboxylated biomass by injecting subcritical liquid carbon dioxide at a pressure of at least 65 bars and a temperature of less than 31° C., using a mass ratio carbon dioxide to biomass of at least 10 kg CO 2 /kg biomass and for a period of time ranging between 30 minutes and 8 hours;

f) Retrieving the extraction product from step e) from the first vessel and loading it onto a support selected from celite, acidic, neutral or basic alumina or silica with a mass ratio extraction product to support ranging between 1 and 20 mass %;

g) Loading the support of step f) into the second vessel;

h) Submitting the second vessel of step g), containing a support loaded with the extraction product, to a flow of subcritical liquid carbon dioxide at a mass ratio carbon dioxide to extraction product of at least 10 kg CO 2 /kg extraction product and for a period of time ranging between 30 minutes and 8 hours in order to separate cannabidiol; and

i) Separating and retrieving cannabidiol.

2 . The method of claim 1 wherein the milled biomass has a density of at least 0.3 g/ml.

3 . The method of claim 1 wherein the decarboxylation is carried out at a temperature of at least 100° C. for a period of time of at least 1 hour.

4 . The method of claim 1 wherein the pressure for the extraction step e) is of at least 90 bars.

5 . The method of claim 1 wherein the temperature in extraction step e) is of at most 25° C.

6 . The method of claim 1 wherein the extraction step is carried out using subcritical carbon dioxide at a mass ratio carbon dioxide to biomass of at least 25 kg CO 2 /kg biomass.

7 . The method of claim 6 wherein the mass ratio carbon dioxide to biomass is of at least 30 kg CO 2 /kg biomass.

8 . The method of claim 1 wherein the support of step f) is selected from basic alumina in order to separate CBD with undetectable levels of THC.

9 . The method of claim 1 wherein in step f), the extraction product from the first vessel is loaded onto the support with a mass ratio extraction product to support ranging between 5 and 10 mass %.

10 . The method of claim 1 , including the additional step of:

(j) continuing the separation process by submitting the second vessel to a flow of supercritical carbon dioxide at a mass ratio carbon dioxide to extraction product of at least 10 kg CO 2 /kg extraction product and for a period of time ranging between 30 minutes and 8 hours in order to separate the remaining products from the support, said products comprising traces of cannabidiol, Δ9-THC and Δ8-THC, and other cannabinoids.

11 . The method of claim 1 wherein the extraction and separation steps are carried out sequentially in a continuous process and wherein the extraction vessel and the separation vessel are connected to one another, which comprises the steps of:

A) Providing 2 vessels connected to each other;

B) Milling dried hemp biomass in order to obtain a product having a bulk density of at least 0.2 g/cm 3 ;

C) Decarboxylating the dried biomass of step B);

D) Filling the first vessel with the milled and decarboxylated biomass of step C);

E) Filling the second vessel with a support selected from celite, acidic, neutral or basic alumina or silica:

F) In the first vessel, extracting a product comprising cannabidiol, Δ9-THC and Δ8 -THC and other cannabinoids from the milled and decarboxylated biomass using subcritical liquid carbon dioxide at a pressure of at least 65 bars and a temperature of less than 31° C., with a mass ratio carbon dioxide to biomass of at least 10 kg CO 2 /kg biomass and for a period of time ranging between 30 minutes and 8 hours;

G) Flowing the extraction product of step F) into the second vessel filled with support and submitting said second vessel to the same flow of subcritical liquid carbon dioxide using the same mass ratio carbon dioxide to biomass, the same temperature and the same pressure as in the first vessel and for a period of time ranging between 30 minutes and 8 hours; and

H) Separating and retrieving cannabidiol.

12 . The method of claim 11 wherein the pressure for the extraction step F) is of at least 90 bars.

13 . The method of claim 11 wherein the temperature in extraction step F) is of at most 25° C.

14 . The method of claim 11 wherein the support of step E) is selected from basic alumina in order to separate CBD with undetectable levels of THC.

15 . The method of claim 11 , including the additional step of:

I) continuing the separation process by submitting the second vessel to a flow of supercritical carbon dioxide at a mass ratio carbon dioxide to extraction product of at least 10 kg CO 2 /kg extraction product and for a period of time ranging between 30 minutes and 8 hours in order to separate the remaining products from the support, said products comprising traces of cannabidiol, Δ9-THC and Δ8-THC, and other cannabinoids.