One-step pyrolysis-catalytic hydrogen production by the oleaginous microalga Chromochloris zofingiensis

Abstract

In this study, one-step pyrolysis-catalytic hydrogen production was developed with the substance of a typical oleaginous microalga, Chromochloris zofingiensis, with Ni/Zr0.2Ce0.8O2 as the catalyst. Our results demonstrated that the formation of a ZrO2–CeO2 solid provided thermal stability to the catalyst and showed abundant active sites for catalysis. Moreover, 450 °C was the optimum temperature for hydrogen production by microalgae. At this temperature, hydrogen production reached 25.47 mmol g−1, with hydrogen accounting for 43.5 % of the total gas, comparable to results previously reported for “two-step” hydrogen production methos. Further studies showed that lipids within microalgal cells were the major substance for hydrogen production, whereas starch and protein had limited hydrogen-producing capabilities. Therefore, by increasing the lipid content to 33.1 % of cell dry weight through abiotic stress, the hydrogen yields significantly improved, reaching 47.71 mmol g−1, with hydrogen constituting 69.4 % of the total gas. In summary, our study proved that oleaginous microalgae were feasible feedstock for one-step pyrolysis-catalytic hydrogen production.