Nitrogen-doped hydrothermal carbon as a catalyst for selective alkoxyphenol production from pine pyrolysis

Nitrogen-doped activated carbon (NAC) has shown great potential in selectively catalyzing the pyrolysis of biomass to produce alkoxyphenols, with the structural characteristics being key to influencing alkoxyphenol yields. In this study, a method for preparing nitrogen-doped hydrothermal carbon (HY-NAC) by hydrothermal carbonization coupled with ammonia water activation was proposed. The resulting carbon was then used as catalyst in the selective preparation of alkoxyphenols by catalytic pyrolysis of biomass, with the 9,10-dihydroanthracene (DHA) being selected as the hydrogen donor. The physical and chemical properties of HY-NAC were systematically studied. Based on the pyrolysis-gas chromatography/mass spectrometry, the effects of the carbonization method and ammonia concentration during HY-NAC preparation, and the pyrolysis temperature, catalyst/pine ratio, and DHA/pine ratio during the pyrolysis process on the yields of alkoxyphenols were investigated. The results showed that, compared to the activated carbon prepared by pyrolytic carbonization method, HY-NAC had a larger specific surface area, higher nitrogen content, and higher contents of pyridinic nitrogen and pyrrolic nitrogen, thus exhibiting stronger catalytic performance. At an ammonia concentration of 10 %, the specific surface area of HY-NAC was 947.488 m 2 /g, and the relative contents of pyridinic nitrogen and pyrrolic nitrogen were 38.04 % and 33.22 %, respectively. Under pyrolysis temperature of 500 °C, HY-NAC/pine ratio of 3:1, and DHA/pine ratio of 1:1, the alkoxyphenol yield reached the maximum of 7.42 wt%.