A process of preparing an alkali salt solution for the production of catalysts or promoters of catalysts, the process comprising the steps of: (i) Passing a solution containing a mixture of potassium, rubidium and caesium sulfates through an evaporative crystallisation step to obtain a potassium containing salt, and a solution comprising rubidium and caesium sulfate; (ii) Further evaporative crystallisation of the liquid product of step (i) to obtain a rubidium containing salt and a solution enriched in caesium sulfate; and (iii) Mixing one or more of the obtained salts and the solution at a desired ratio to prepare the alkali salt solution.

A process of preparing an alkali salt solution for the production of catalysts or promoters of catalysts, the process comprising the steps of: (i) Passing a solution containing a mixture of potassium, rubidium and caesium sulfates through an evaporative crystallisation step to obtain a potassium containing salt, and a solution comprising rubidium and caesium sulfate; (ii) Further evaporative crystallisation of the liquid product of step (i) to obtain a rubidium containing salt and a solution enriched in caesium sulfate; and (iii) Mixing one or more of the obtained salts and the solution at a desired ratio to prepare the alkali salt solution.

A heat-insulating transparent PVC sheet is formed from a PVC substrate having a thickness of 0.02-2.0 mm and contains heat-insulation pastes evenly distributed over the PVC substrate, since the heat-insulation paste contains an essential component of wolfram cesium powder (WCs) with a chemical formula of Cs.sub.XN.sub.YWO.sub.3-ZCl.sub.C and having a particle size of 0.005-2 m, the heat-insulating transparent PVC sheet has an excellent weatherability, and particularly before and after tested in 300-hour service life in line with ASTM G-154 specification, has a physical property of weatherability decay rate (%) small than 4%.

A heat-insulating transparent PVC sheet is formed from a PVC substrate having a thickness of 0.02-2.0 mm and contains heat-insulation pastes evenly distributed over the PVC substrate, since the heat-insulation paste contains an essential component of wolfram cesium powder (WCs) with a chemical formula of Cs.sub.XN.sub.YWO.sub.3-ZCl.sub.C and having a particle size of 0.005-2 m, the heat-insulating transparent PVC sheet has an excellent weatherability, and particularly before and after tested in 300-hour service life in line with ASTM G-154 specification, has a physical property of weatherability decay rate (%) small than 4%.

A method for producing ethylene oxide comprising: a) providing one or more feed components, wherein the one or more feed components contains at least ethylene obtained by dehydrating ethanol; b) contacting the one or more feed components with an ethylene oxide catalyst bed disposed in a reactor tube, the ethylene oxide catalyst bed comprising: (1) an upstream ethylene oxide catalyst having a first cesium concentration and (2) a downstream ethylene oxide catalyst having a second cesium concentration, wherein the first cesium concentration is higher than the second cesium concentration.

Described are luminescent components with excellent performance and stability. The luminescent components comprise a first element 1 including first luminescent crystals 11 from the class of perovskite crystals, embedded a first polymer P1 and a second element 2 comprising a second solid polymer composition, said second polymer composition optionally comprising second luminescent crystals 12 embedded in a second polymer P2. Polymers P1 and P2 differ and are further specified in the claims. Also described are methods for manufacturing such components and devices comprising such components.

The present invention relates to a cesium borosilicate compound, a nonlinear optical crystal of cesium borosilicate, and a preparation method therefor and a use thereof. The cesium borosilicate compound has a chemical formula of Cs.sub.2B.sub.4SiO.sub.9 and a molecular weight of 481.15, and is prepared using a solid phase method. The nonlinear optical crystal of the cesium borosilicate compound has a chemical formula of Cs.sub.2B.sub.4SiO.sub.9 and a molecular weight of 481.15, does not have a center of symmetry, belongs to the tetragonal system with space group I4 and unit-cell parameters a=6.731(3) , c=9.871(9) and V=447.2(5) .sup.3, and has a wide transmittance range. The shortest ultraviolet cutoff edge is smaller than 190 nm, the frequency doubling effect of the crystal is 4.6 KDP, and the crystal is grown by a high-temperature solution spontaneous crystallization method and a flux method. The crystal has advantages of high growth rate, being transparent and inclusion free, low cost having a wide transmittance range, high hardness, good mechanical property, being crack resistant and not prone to deliquescence, being easy to process and store, and the like. The crystal is widely applied to manufacturing of nonlinear optical devices such as frequency doubling generators, frequency up-converters, frequency down-converters or optical parametric oscillators.

The present invention relates to a cesium borosilicate compound, a nonlinear optical crystal of cesium borosilicate, and a preparation method therefor and a use thereof. The cesium borosilicate compound has a chemical formula of Cs.sub.2B.sub.4SiO.sub.9 and a molecular weight of 481.15, and is prepared using a solid phase method. The nonlinear optical crystal of the cesium borosilicate compound has a chemical formula of Cs.sub.2B.sub.4SiO.sub.9 and a molecular weight of 481.15, does not have a center of symmetry, belongs to the tetragonal system with space group I4 and unit-cell parameters a=6.731(3) , c=9.871(9) and V=447.2(5) .sup.3, and has a wide transmittance range. The shortest ultraviolet cutoff edge is smaller than 190 nm, the frequency doubling effect of the crystal is 4.6 KDP, and the crystal is grown by a high-temperature solution spontaneous crystallization method and a flux method. The crystal has advantages of high growth rate, being transparent and inclusion free, low cost having a wide transmittance range, high hardness, good mechanical property, being crack resistant and not prone to deliquescence, being easy to process and store, and the like. The crystal is widely applied to manufacturing of nonlinear optical devices such as frequency doubling generators, frequency up-converters, frequency down-converters or optical parametric oscillators.

Methods to recover or separate cesium formate or rubidium formate or both from a mixed alkali metal formate blend are described. One method involves adding cesium sulfate or rubidium sulfate to the mixed alkali metal formate blend in order to preferentially precipitate potassium sulfate from the mixed alkali metal formate blend. Another method involves adding cesium carbonate or cesium bicarbonate or both to preferentially precipitate potassium carbonate/bicarbonate and/or other non-cesium or non-rubidium metals from the mixed alkali metal blend. Further optional steps are also described. Still one other method involves converting cesium sulfate to cesium hydroxide.

Methods to recover or separate cesium formate or rubidium formate or both from a mixed alkali metal formate blend are described. One method involves adding cesium sulfate or rubidium sulfate to the mixed alkali metal formate blend in order to preferentially precipitate potassium sulfate from the mixed alkali metal formate blend. Another method involves adding cesium carbonate or cesium bicarbonate or both to preferentially precipitate potassium carbonate/bicarbonate and/or other non-cesium or non-rubidium metals from the mixed alkali metal blend. Further optional steps are also described. Still one other method involves converting cesium sulfate to cesium hydroxide.