| abstract |
An ebullated bed hydroprocessing system is upgraded using a dual catalyst system that includes a heterogeneous catalyst and dispersed metal sulfide particles, which permits recycling of vacuum bottoms without recycle buildup of asphaltenes. The dual catalyst system more effectively converts asphaltenes in the ebullated bed reactor and increases asphaltene conversion by an amount that at least offsets higher asphaltene concentration resulting from recycling of vacuum bottoms. In this way, there is no recycle buildup of asphaltenes in upgraded ebullated bed reactor notwithstanding recycling of vacuum bottoms. In addition, residual dispersed metal sulfide catalyst particles in the vacuum bottoms can maintain or increase the concentration of the dispersed metal sulfide catalyst in the ebullated bed reactor. |