Powder-containing chambers, vibrated vertically, can serve as micro-reactors answering questions of several kinds: How does a particular gas-solid reaction respond to axial gas mixing? What are the outcomes for a reaction conducted at high pressure? How might a reaction respond to unsteady-state reaction environments (whereby, for example, powder-contacting alternates between short exposure to a reaction gas and long exposure to a treating gas)? Answers can guide the planning of fluid-bed research and development. (C) 2004 Elsevier B.V. All rights reserved.