Investigation of product selectivity and kinetics of poplar sawdust catalytic pyrolysis over bi-metallic Iron-Nickel/ZSM-5 catalyst.

Py-GC/MS and thermogravimetric analysis were carried out to systematically explore product selectivity and kinetics of poplar sawdust catalytic pyrolysis over bi-metallic Fe-Ni/ZSM-5. The results showed that the Fe-Ni/ZSM-5 exhibited an additive effect on the production of monocyclic aromatic hydrocarbons compared to mono-metallic catalysts (Fe/ZSM-5 or Ni/ZSM-5). Fe-Ni/ZSM-5 further increased the yield of toluene (17.28 mg g-1), which was 41.4% and 80.9% higher than Fe/ZSM-5 and Ni/ZSM-5, respectively. According to the kinetic analysis, the average activation energy obtained from catalytic pyrolysis with Fe-Ni/ZSM-5 using the methods of Friedman, Starink, Flynn-Wall-Ozawa, and Kissinger-Akahira-Sunose was 156.19, 152.39, 154.30, and 152.11 kJ mol-1, respectively. Fe-Ni/ZSM-5 addition lowered the activation energy compared to non-catalytic pyrolysis at the conversion rate of 0.15-0.75. The overall catalytic pyrolysis process of poplar sawdust follows the diffusion and nucleation models. The thermodynamic parameters (enthalpy and entropy) showed positive and negative values, respectively, indicating non-spontaneous reactions during the catalytic pyrolysis process.

Stainless steel membranes for harvesting cyanobacteria: Performance, fouling and cleaning.

Stainless steel membranes with 0.45, 1 and 2 µm pore sizes were applied to harvest cyanobacteria. Their critical fluxes were determined and continuous filtration tests were conducted. Two novel transition-combined models for constant flux filtration were developed and applied to describe observed variations in fouling. A pyrolysis cleaning method was proposed and tested. The results showed that the 2 µm membrane was preferable for practical applications as it could process more than twice the filtrate volume before clogging than the other two membranes, with an 8% reduction in rejection rate. The transition-cake-intermediate model predicted fouling better than the combined models, and the fouling mainly resulted from cake formation. Pyrolysis cleaning removed the foulants more effectively and quicker while converting the foulants into desirable products, making it a promising cleaning method for heat-resisting membranes fouled by algae. But both cleaning methods could lead to the enlargement of pore sizes and porosity.