Synthesis Of Mesoporous Alumina And Its Application In Diesel Hydrodesulfurization

With the rapid development of modern industry,air pollution has become increasingly serious and has attached widespread attention.Sulfide is one of the main pollutants,which is produced during the use of fuel.Therefore,it is necessary to carry out ultra-deep desulfurization of oil.At present,hydrotreating technology is the most effective method in large-scale for low-sulfur fuel production.Thus the design and development of novel and highly active catalysts is the key to achieve the goal for the production of ultra-low sulfur clean fuel.The difficulty of ultra-deep HDS lies in the removal of macromolecular sulfides,such as dibenzothiophene?DBT?,which requires the catalyst to have open pores and requires the traditional alumina support to have a mesoporous structure.The templating agent plays a vital role in the synthesis process.In this paper,commercial cellulose CNF?cellulose nanofiber?,MCC?microcrystalline cellulose?and natural straw,and cotton cellulose were used as templates.At the same time,the effects of the addition amount of these templating agents on the pores of the supports were investigated.The supports were prepared by a two-step impregnation method to prepare Ni Mo hydrodesulfurization catalysts.And DBT was used as diesel model sulfide to evaluate the HDS performances of these catalysts.At the same time,in order to further study the structure-activity relationship between catalytic activity and catalyst physicochemical properties,X-ray diffraction?XRD?,nitrogen adsorption desorption,Raman spectroscopy?Raman?,high resolution transmission electron microscopy?HRTEM?and other characterization methods were used to analysis the properties of catalysts and supports.The results show that not only the open mesoporous structure can be synthesized,but also the interaction between the support and active metal can be weakened with the addition of CNF.With the increasing of the addition amount,the pore size increased firstly and then decreased.When the CNF addition amount was 0.7g,the pore size of CNF-4 was 5.6nm.The DBT conversion over Ni Mo/CNF-4 catalyst was92.3%,and the ratio of the path selectivity?HYD/DDS?is 0.41.For the MCC templating series,when the MCC amount was 0.4g,the pore diameter of the synthesized MCC-1 was 5.4 nm,the activity of the corresponding catalyst Ni Mo/MCC-1 was the highest,and the DBT conversion approached 93%and HYD/DDS was 0.26.For natural cotton and straw series,although the ability of increasing the pore size was not as good as commercial cellulose of MCC and CNF,it can also meet the mesoporous size requirements.In the DBT HDS reaction,it exhibited excellent catalytic activity.When the cotton addition amount was 0.8 g,the pore diameter reached 5.4 nm,and at a space velocity of 20 h^-1,the DBT conversion rate reached97%.When the amount of straw amount was 1.6 g,the pore diameter was 5.1 nm,and the DBT conversion rate was 90%.This research lays a foundation for the synthesis of mesoporous alumina with green renewable cellulose as template.It has certain reference and guiding significance for the development of high performance industrial HDS catalyst.