US 11,814,339 B2
Method for preparing isocyanate in gaseous phase
Weiqi Hua, Shandong (CN); Tonghe Li, Shandong (CN); Yonghua Shang, Shandong (CN); Shuchang Sun, Shandong (CN); Jingxu Wang, Shandong (CN); Jinping Han, Shandong (CN); Qiang Li, Shandong (CN); Wenbin Li, Shandong (CN); Jing Li, Shandong (CN); Pengfei Wang, Shandong (CN); and Yuan Li, Shandong (CN)
Assigned to WANHUA CHEMICAL GROUP CO., LTD., Shandong (CN); and WANHUA CHEMICAL (NINGBO) CO., LTD., Ningbo (CN)
Appl. No. 17/295,806
Filed by WANHUA CHEMICAL GROUP CO., LTD., Shandong (CN); and WANHUA CHEMICAL (NINGBO) CO., LTD., Ningbo (CN)
PCT Filed Dec. 26, 2018, PCT No. PCT/CN2018/123876
§ 371(c)(1), (2) Date May 20, 2021,
PCT Pub. No. WO2020/132936, PCT Pub. Date Jul. 2, 2020.
Prior Publication US 2022/0024863 A1, Jan. 27, 2022
Int. Cl. C07C 263/10 (2006.01); C07C 265/06 (2006.01)
CPC C07C 263/10 (2013.01) [C07C 265/06 (2013.01)] 18 Claims
 
1. A method for preparing an isocyanate in a gas phase, comprising: feeding an amine-containing gas stream and a phosgene-containing stream into a reaction zone in the presence or absence of an inert gas, allowing the amine and the phosgene to contact in gaseous forms and undergo a phosgenation reaction in the reaction zone, thus preparing the isocyanate in the reaction zone; wherein the phosgene-containing stream is preheated before entering the reaction zone and the phosgene-containing stream comprises a substance A with a mass fraction smaller than 0.5% before being preheated, wherein the substance A is a substance containing non-target isocyanate (NCO) groups and olefinic double bonds;
where before preheated, the phosgene-containing stream is treated through one or a combination of at least two of rectification, adsorption, and scrubbing such that the mass fraction of the substance A contained in the phosgene-containing stream is controlled.