Dioxin refers to the collectively chlorine-containing organic compounds which contain one or two oxygen-bond connecting with two benzene rings, the carcinogen with most toxic, very stable and difficult to break down, besides, the dioxin has reproductive, immunity and endocrine toxicity. The main active ingredients of de-dioxin catalyst are titanium dioxide, vanadium pentoxide, tungsten trioxide, cobalt oxide and other transition metal oxides, or a noble metal (platinum, gold, etc.). The researches on an efficient, economic catalyst with both functions of de-dioxin and denitration catalyst is very necessary.

 

Waste hydrodesulfurization catalyst generated by the refinery contains a lot of metals, such as aluminum, tungsten, nickel, cobalt, vanadium, which is a relatively inexpensive resource. The recycling of it can not only recycle the useful resources, but also reduce the environmental pressure, and thus become a hot topic. Experiments have shown that the waste hydrodesulfurization catalyst can be used to prepare tungsten trioxide contained of de-dioxin and denitration catalyst, and prepared as follows:

 

1. Waste hydrodesulfurization catalyst is carried out a pretreatment by washing with deionized water and drying;

2. Mix the carrier-titanium dioxide and the active ingredient-tungsten trioxide. The ammonium metatungstate and titanate are mixed according to mass ratio of 1: 9 to give a suspension, then filtered and the wet powder is calcined, to obtain the titanium dioxide loading with tungsten trioxide;

3. Ball grinding to mix the waste hydrodesulfurization catalyst and the carrier to obtain a raw material mixed powder, adding oxalic acid (or citric acid) and water to mix uniformly at the same time;

4. Dry and calcine the semi-finished products o give the finished-products--tungsten trioxide catalyst with the function of both de-dioxin and denitration.