Refinig in distillation columns just separates stuff based on the boiling point. Cracking is the step that breaks up long molecules into shorter ones, basically a supply-demand thing because there is more demand for e.g. gasoline than tar and pitch. The molecular sieve in the news will only replace the distillation column (and probably not all of them, since you need several different ones). So, the dirty part, which is cracking, will largely remain the same and the flares aren't going anywhere either. But, yeah, the process will be made a bit more energy efficient (hopefully). But on the other hand, the refineries generate their own energy by burning the heaviest molecules which are is much smaller demand and are very cheap. So those membranes better be dirt cheap, too. Another thing is that pushing stuff through membranes takes a lot of electrical energy to run the pumps, while running a distillation column just needs thermal energy. While the refinery can easily make thermal energy internally by burning the heavy fractions, it will either need to purchase the electricity externally, or install a turbine to make the electricity from steam, which is expensive. The commercial success of the membranes thus depends on cheap electricity, too.