Process for preparing chlorine from HCI

A process for preparing chlorine, the process comprising:

• introducing hot nitrogen into a fluidized-bed reactor to heat the fluidized-bed reactor to a first temperature in a first heating phase;
• feeding hydrogen chloride and oxygen into the fluidized-bed reactor and reacting the hydrogen chloride and oxygen, thereby heating the fluidized-bed reactor to an operating temperature of from 350 to 420° C. in a second heating phase;
• further reacting hydrogen chloride with oxygen in the presence of a particulate catalyst in the fluidized-bed reactor at the operating temperature in an operating phase;
• and
• circulating water in a tube of a shell-and-tube heat exchanger to remove heat from the fluidized-bed reactor,
• wherein:
• the first temperature is below the operating temperature;
• the operating temperature is increased during the operating phase to counter a decrease in HCl conversion due to progressive deactivation of the particulate catalyst;
• the first heating phase occurs before the hydrochloric acid and oxygen are introduced into the fluidized-bed reactor;
• and
• the first heating phase further comprises circulating a heat transfer medium in the tube of the shell-and-tube heat exchanger to heat the shell-and-tube heat exchanger, thereby heating the fluidized-bed reactor;
• wherein the HCl:O2 ratio is reduced during the operating phase to counter a decrease in HCl conversion due to progressive deactivation of the particulate catalyst.