Abstract: An Anti-gelling agent for a hydrocarbon mixture containing a conjugated diene, which comprises (a) at least one compound selected from the group consisting of compounds having an NO radical in the molecule, and precursor compounds capable of forming an NO radical, (b) a phosphorus-containing compound, and (c) at least one compound selected from the group consisting of heterocyclic aldehydes, aromatic aldehydes and condensates of these aldehydes. Clogging in an apparatus for separating and refining a hydrocarbon mixture containing a conjugated diene can be prevented by adding the anti-gelling agent in the apparatus.

Abstract: The invention relates to a polymerization inhibitor comprising at least one compound (a) selected from the group consisting of a compound having an NO radical in its molecule and a precursor compound capable of forming an NO radical, and a phosphorus-containing compound (b), wherein a weight ratio of the compound (a) to the phosphorus-containing compound (b) is 1:10 to 100:1. Specifically, the invention provides a method for inhibiting the polymerization of at least one monomer (c) selected from the group consisting of a conjugated diene, an aromatic vinyl, an ethylenically unsaturated nitrile and an &agr;-olefin, comprising causing the polymerization inhibitor to coexist with the monomer (c), and a polymerization-inhibiting composition comprising the polymerization inhibitor and the monomer (c).

Abstract: There is provided a water absorbent comprising a magnetic material and a highly water-absorbable resin. Said water absorbent is contacted with a moisture-containing powder and the water absorbent that has absorbed the moisture is then separated from the powder by means of a magnet, whereby the moisture content of the moisture-containing powder can be decreased. Said water absorbent is produced by forming a mixture composed of the highly water-absorbable resin, water and the magnetic material and then drying said mixture.