Complex sentence: The Qing Daoguang Emperor, pleased to hear of Jardine's departure, then proceeded to appoint a special Commissioner, Lin Zexu, to stop the opium trade altogether, at that time centred around Canton.
Split into simpler sentences: The Qing Daoguang Emperor, pleased to hear of Jardine's departure, then proceeded to stop the opium trade. He appointed Commissioner Lin Zexu, specifically to suppress the opium trade, at that time centred around Canton.