A proton conducting ceramic membrane comprising a conducting layer, wherein said conducting layer comprises a mixture of a rare-earth tungstate as herein defined and a mixed metal oxide as herein defined. The invention also relates to a reactor comprising said membrane and the use of said membrane in a dehydrogenation process.

A process for preparing a refractory brick, comprises: mixing a refractory aggregate and a binder composition to obtain a refractory mixture wherein the binder composition comprises:

(a) carbohydrate reactant(s) comprising reducing sugar(s) or carbohydrate reactant(s) that yield reducing sugar(s) in situ under thermal conditions and nitrogen-containing reactant(s) and/or

(b) curable reaction product(s) of reducing sugar(s) and nitrogen-containing reactant(s) pressing the refractory mixture to obtain a moulded refractory brick; and firing the moulded refractory brick.

The disclosure provides a refractory brick system comprising a chromia refractory brick for operation in the slagging environment of an air-cooled gasifier. The chromia refractory brick comprises a ceramically-bonded porous chromia refractory having a porosity greater than 9% and having carbon deposits residing within the pores. The brick may be further comprised of Al.sub.2O.sub.3. The air-cooled gasifier generates a liquefied slag in contact with the refractory brick and generally operates at temperatures between 1250 C. and 1575 C. and pressures between 300 psi to 1000 psi, with oxygen partial pressures generally between 10.sup.4 and 10.sup.10 atm. The refractory brick performs without substantial chromium carbide or chromium metal formation in the low oxygen partial pressure environment. The inclusion of carbon without chromium carbide formation provides for significant mitigation of slag penetration and significantly reduced refractory wear.