The inventions relate to controlling the particle size, and gas flows in moving beds of particles containing metallic iron and/or nickel, wherein the metallic iron or nickel are reactants in carbonylation reactions with carbon monoxide (a component of the flowing gas). The inventions' use is to increase the rates of production of iron carbonyl and nickel carbonyl. The inventions use cross-flow funnels containing moving beds of carbonylation particles (i.e., that contain iron and nickel) and regulation of the removal of those particles from the bottoms of the funnels. Cross-flow refers to the horizontal flow of the carbonylation gas (containing carbon monoxide) through the downward moving beds of carbonylation particles held in the cross-flow funnels.

Disclosed is a hydrocarbon conversion process in which an alkane component is catalytically converted in the presence of an oxygen or oxidizing component (i.e., oxidant). The hydrocarbon conversion process can be an oxidative coupling reaction, which refers to the catalytic conversion of alkane in the presence of oxidant to produce an olefin product, i.e., a composition containing C.sub.2+ olefin. Reverse-flow reactors can be used to carry out the oxidative coupling reaction.

Processes for producing activated chromium catalysts such as chromium/silica catalysts and titanated chromium/silica catalysts are disclosed, and these processes utilize a multistep process involving exposure to inert and oxidizing atmospheres at specific temperature conditions. The resulting activated chromium catalysts have unexpectedly high melt index potential and can produce ethylene-based polymers with lower gel counts in addition to higher melt indices. Related activation systems are provided in which the fluidizing gas entering the fluidized bed vessel can be adjusted between an inert gas, an oxygen-containing gas, or a mixture of the inert gas and the oxygen-containing gas to minimize or prevent exotherms.

A method of operating a gas-solid fluidized bed (130) includes-flowing a pulsating gas flow upwards through a bed of solid particles from a distributor (104) to cause a dynamically structured bubble flow (130), and processing particles using the fluidized bed.