Production of crude bio-oil and biochar from hydrothermal conversion of jujube stones with metal carbonates

In this study, hydrothermal processing was employed to produce crude bio-oil and biochar from waste jujube stones by deploying metal carbonates as catalysts. The effects of metal carbonate catalysts (K2CO3, Na2CO3 and SrCO3) in different concentrations on the product yields and properties were tested for the conversion studies. The use of metal carbonates (K2CO3, Na2CO3 and SrCO3) increased the yield of bio-oil almost twofold, with the highest yield (18.66 wt%) obtained using K2CO3 at a concentration of 10 wt%. (E)- 9-octadecenoic acid (elaidic acid), 2,6-dimethoxyphenol (syringol) and 2-methoxyphenol (guaiacol) were some of the prominent compounds found in the crude bio-oils. The process also resulted in an efficient conversion of jujube stones to biochar with high content of oxygenated functional groups which makes it an effective precursor for various applications. The heating values of the bio-oils and biochars were significantly improved compared to those of the feedstock.