High Performance Reactor for Polysulfide Production, 1999 Pulping Conference Proceedings

H. Nishijima, S. Hirohama & H.Nakamura

Environmental Technology Dept.

Research & Development Center

A new technique is devised to significantly improve the performance of the polysulfide process, which employs a trickle bed reactor to oxidize Na2S in white liquor to polysulfide by air using activated carbons as the catalyst. The technique consists of a new catalyst and a reactor design for maximizing catalyst performance.

The catalyst is obtained by optimizing the density of active sites at the catalytic surface. The reaction rate increases as the density increases in the low-density region. However, the reaction rate decreases above a certain value of the density because liquid layer grows in the macro-pore and/or between the catalyst particles and eventually reduces the mass-transfer rate of oxygen. We propose the industrial catalyst with the optimum density of the active sites.

To establish the reactor design we examined the effect of the linear velocities of liquid and gas on mass-transfer rate of oxygen at the catalyst. The reactor volume is minimized by optimizing the linear velocities under process constraints.