本发明涉及一种气相法制备低水解氯含量异氰酸酯的方法，在有或无惰性介质存在的条件下，使相应的胺与化学计量过量的光气在反应区中进行光气化反应，其中反应条件的选择使得至少反应组分胺、异氰酸酯和光气在这些条件下为气态，和将至少一种包含胺的气流和至少一种包含光气的气流供入反应区内，在反应区后端的淬冷区引入二氧化碳流股，二氧化碳流股的摩尔含量小于光气料流摩尔量的60％，可以更容易获得低水解氯含量的异氰酸酯，提高产品收率，降低装置投资成本。

The invention relates to a method for preparing isocyanate with low hydrolytic chlorine content by a gas phase method, which comprises the following steps of: carrying out phosgenation reaction on corresponding amine and stoichiometric excess phosgene in a reaction zone in the presence or absence of an inert medium; wherein the reaction conditions are selected such that at least the reaction components amine, isocyanate and phosgene are gaseous under these conditions, and feeding of at least one gas stream comprising amine and at least one gas stream comprising phosgene into the reaction zone, and introducing of a carbon dioxide stream in a quenching zone at the rear end of the reaction zone are carried out, and the molar content of the carbon dioxide stream is less than 60% of the molar weight of the phosgene stream, so that the isocyanate with low hydrolytic chlorine content can be obtained more easily, the product yield is improved, and the investment cost of the device is reduced.