Abstract: A process is proposed for cleaning an apparatus to remove deposits from a process for the recovery of purified N-methylpyrrolidone (NMP) by evaporating NMP from a contaminated NMP stream which is obtained in a process for the extractive separation of acetylene from the reaction mixture of a partial oxidation of hydrocarbons after expulsion of the acetylene as a gas, wherein hot water is passed into the apparatus and is stirred.

Abstract: The invention relates to the use of a thermoelectric material for thermoelectric purposes at a temperature of 150 K or less, said thermoelectric material is a material corresponding to the stoichiometric formula FeSb2, wherein all or part of the Fe atoms optionally being substituted by one or more elements selected from the group comprising: Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Tr, Pt, Au, Hg, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and a vacancy; and wherein all or part of the Sb atoms optionally being substituted by one or more elements selected from the group comprising: P, As, Bi, S, Se, Te, B, Al, Ga, In, Tl, C, Si, Ge, Sn, Pb and a vacancy; with the proviso that neither one of the elements Fe and Sb in the formula FeSb2 is fully substituted with a vacancy, characterised in that said thermoelectric material exhibits a power factor (S2?) of 25 ?W/cmK2 or more at a temperature of 150 K or less.

Abstract: A process is proposed for cleaning an apparatus to remove deposits from a process for the recovery of purified N-methylpyrrolidone (NMP) by evaporating NMP from a contaminated NMP stream which is obtained in a process for the extractive separation of acetylene from the reaction mixture of a partial oxidation of hydrocarbons after expulsion of the acetylene as a gas, wherein hot water is passed into the apparatus and is stirred.