The present disclosure relates to a device for gas conversion comprising a plasma reactor and a chamber configured for receiving a gas flow of converted and unconverted feed gas evacuated from the plasma reactor. The chamber comprises a supply throughput for filling the chamber with solid reactant material so as to form the fixed bed of solid reactant material, and at least one gas exhaust window for extracting a product gas. The device for gas conversion further comprises a silo for storing a stock of the solid reactant material and a connecting tube connecting a bottom opening of the silo with the supply throughput of the chamber. The silo and the connecting tube are configured such that, when the device is in operation and solid reactant material is being depleted in the chamber, a flow of solid reactant material from the silo to the chamber is induced so as to maintain the chamber filled with solid reactant material, and wherein the flow of solid reactant material from the silo to the chamber is induced by a gravitational force or at least partly by a gravitational force. The present disclosure also relates to a method for gas-conversion.