Optimization of waste paper’s catalytic cracking to liquid fuel using copper slag as the catalyst based on response surface methodology

In this paper, copper slag was used as a catalyst in the catalytic pyrolysis of waste paper to obtain liquid fuel. The experiments were conducted in a fixed bed reactor. The results demonstrated that copper slag could significantly reduce the viscosity of bio-oil by 59%. Under different pyrolysis temperature, catalyst ratio and waste paper mass, the yield of pyrolytic liquid and the viscosity of bio-oil were modeled and analyzed using the response surface method (RSM). Multi-response variable optimization analysis indicated that the optimum values for the yield and viscosity were 39.13% and 3.81 mPa·s, respectively. For the pyrolysis process, the optimum values for pyrolysis temperature, catalyst ratio and the mass of waste paper were found to be 495 °C, 20%, and 500 g, respectively. Finally, physical and chemical characterizations of the obtained bio-oil under optimum pyrolysis conditions were conducted using viscometer, pH meter and gas chromatography-mass spectrometry (GC-MS) analyses. This study has certain guiding significance for optimizing the pyrolysis process of waste paper and improving the quality of bio-oil. •The viscosity of bio-oil can be significantly reduced by using copper slag.•The pyrolysis liquid yield and bio-oil viscosity were modeled based on the RSM.•The best pyrolysis conditions for high-yield, high-quality bio-oil were obtained.