Abstract: Monomeric styrene is recovered from plastics waste containing styrene polymers by thermal depolymerization by a process in which the waste is transported in liquid or solid form into a fluidized bed of a solid heat transfer agent and is cracked or depolymerized in an average residence time of less than 60 seconds and styrene is obtained from the gaseous crack products. Preferably, magnesium aluminum silicate is used as a heat transfer agent and C.sub.1 -C.sub.6 -hydrocarbons formed as byproducts in the depolymerization are used as operating gas for maintaining the fluidized bed and are circulated.

Abstract: A process for the preparation of vinyl phosphonic derivatives of the general formula I ##STR1## in which R.sup.1 and R.sup.2 are the same or different and may stand for hydrogen or a C.sub.1 -C.sub.8 -alkyl, a C.sub.6 -C.sub.10 -aryl, or a C.sub.8 -C.sub.10 -aralkyl radical optionally substituted by Cl or Br, and in which R.sup.1 and R.sup.2 may alternatively be joined together to form an alicyclic ring having from 3 to 12 carbon atoms in the ring, wherein an ethane phosphonic ester of the general formula II ##STR2## in which R.sup.3 and R.sup.4 have the meanings stated above for R.sup.1 and R.sup.2 except for hydrogen and X denotes a hydroxy group, a halogen atom, or a radical of the formula--OR.sup.5,in which R.sup.5 is a hydrogen atom or a radical of the formula ##STR3## in which R.sup.6 is a C.sub.1 -C.sub.6 -alkyl radical or an alicyclic ring, is converted in the gas phase in the presence of a solid catalyst.