Pd/C催化氧化吸附脱除燃油中噻吩类硫化物研究

Removal of thiophenic compounds from fuels based on oxidative adsorption with Pd/C

脱硫剂由Pd/C、异丙醇、氢氧化钠和去离子水组成。采用正辛烷作溶剂分别配制以噻吩、二苯并噻吩、4,6-二甲基二苯并噻吩为模型硫化物的模拟油。采用N2吸附等温线、SEM、TEM、XRD对Pd/C结构特征进行了表征。表征结果显示Pd/C的比表面积为1 836 m^2/g,孔容为0.98 cm^3/g,根据其I型吸附等温线可知其绝大部分孔为微孔。由Pd/C的SEM和TEM图可以看出Pd的纳米颗粒比较均匀地分布于碳材料上,Pd金属纳米粒子的直径约3—5 nm。XRD图显示Pd的纳米晶体颗粒的(111)、(200)、(220)和(311)典型晶面的存在,并且负载的Pd大多数是存在于活性炭孔内。采用间歇反应器在60℃温度下,脱硫剂可在3 h内将燃油中硫的质量分数从250 mg/kg降到10 mg/kg以下,从而得到低硫燃油,脱硫剂在FCC汽油中得到较好的验证。Pd/C既作为原位产生过氧化氢的催化剂,又是吸附砜类硫化物的吸附剂,洗脱再生后仍具有较好的催化和脱硫性能。

The desulfurizer was composed of Pd/C,isopropanol,sodium hydroxide and deionized water. The model fuels were prepared by thiophene,dibenzothiophene and 4,6-dimethyldibenzothiophene using n-octane as solvent,respectively. The Pd/C was characterized by N2 adsorption isotherm,SEM,TEM and XRD. The feature of type I isotherm shows that the most pores in Pd/C catalyst are micropores and the BET surface area of Pd/C is 1 836 m^2/g and the pore volume is 0. 98 cm^3/g,respectively. The average particle size of Pd crystal particle shown in SEM and TEM images is about 3-5 nm and the crystal particles of Pd are distributed uniformly on the internal surface of activated carbon which can strengthen the catalytic efficiency and result in strong combination between Pd and activated carbon. Four typical diffraction peaks of Pd indicate the existence of the crystal faces（ 111）,（ 200）,（ 220） and（ 311） in the XRD patterns. The intensity of the XRD pattern of Pd is weak due to most of the crystals exist in the pores of active carbon and little is on the surface of active carbon. By using batch reactor,the sulfurs can be removed from 250 mg/kg to below 10 mg/kg in 3 hours at 60 ℃ and the ultra-low sulfur fuels can be obtained in model fuels. The good results were also achieved in real FCC gasoil. The Pd/C as the catalyst for producing hydrogen peroxide and the adsorbent for removing sulfurs from fuel still has high efficiency after recycle and regeneration.