Controlled precipitation conditions allow the formation of highly porous, spheroidal aggregates of hydrotalcite. The aggregate structure resembles a house-of-cards, being composed of interconnected thin plates. The aggregate size can vary over a range of about 1 to 60 μm by altering precipitation conditions such as mixing shear, temperature, addition rates and addition order. These materials are low in bulk density and highly absorptive. The aggregate structure is maintained during calcination. The micro and meso-pore size distribution is very similar to conventionally prepared hydrotalcite, but the macroporosity is dominated by the voids between spheroids. The characteristics of these aggregates point to potential applications in areas such as catalysis and separation.

Sulfur has been purified by a dynamic pyrolysis procedure that takes into account the unique viscosity-temperature relationship of the liquid. An apparatus is described that incorporates gas-bubbling and rocking to overcome diffusion-limited kinetics. For the first time, a mechanism is proposed for the pyrolytic purification of sulfur based upon Carsul formation and the H2S ↔ H2Sx equilibrium. Infrared methods are delineated for qualitative analysis and quantitative estimates of anion contaminants, including the omnipresent hydrocarbon impurities. Our purified sulfur has a total carbon, oxygen, and hydrogen impurity level of <10 μg/g.