From the title of the article, I thought it would at least spend some paragraphs describing “Cat’ Cracking.”
Refineries until the 1960’s were essentially giant distilleries. There is a natural division of the crude when heated that results in a predictable and steady amount of light products, gasolines, diesels and heavy less desirable products (bunker oil, asphalt bases, etc.).
With modern techniques of so-called “catalytic distilling,” that traditional ratio can be changed to where a column of crude can give something like 95% gasoline and 5% of the others. Diesel, bunker fuel, home heating oil, etc. used to be cheap because every barrel of gasoline caused lots of these low profit products to be made, too. But these products are no longer excess associated products sold for low cost. They now have to be deliberately made and are no longer “along for the ride.”
An expert could describe all this better than I have. But, this article did not talk about this huge technological change in the refining business. It needed to.
Which was why diesel was always cheaper than gas. Then along came ultra low sulfur diesel, which has to be refined even further, similar to the regional specialty blends of gasoline to prevent smog.
Refineries have to switch processes, which means stop making sone products to produce the other products, couple that with reduced refinery capacity and that brings us to where we are at today.
“ I thought it would at least spend some paragraphs describing “Cat’ Cracking.””
Catalytic cracking provides much gasoline blendstock. It’s not as common in Europe and other places with a high demand for diesel and kerosene. Hydrocracking provides those fuels and is more common there.
“With modern techniques of so-called “catalytic distilling,” that traditional ratio can be changed to where a column of crude can give something like 95% gasoline and 5% of the others. Diesel, bunker fuel, home heating oil, etc. used to be cheap because every barrel of gasoline caused lots of these low profit products to be made, too. But these products are no longer excess associated products sold for low cost. They now have to be deliberately made and are no longer “along for the ride.””
Someone played attention to detail.
Correct.
Modern Vis Breakers and Fluid Catalytic Crackers , and Delayed Cokers can crack and coke virtually any of the gas oil and heavier fractions of a barrel of crude. Down to the individual CH2 molecules level then you use zeolites or platinum metal group cats to dimer and trimer them to any CHa+CH2 chain, ring or isomer the heart desires its how much energy , time and effort do you wish to invest.
PAO that’s polyalphaolefins are stitched together molecule by molecule from cracked ethane into ethylene and then CH2 for example its why real synthetic group IV PAO base oils are $12 per quart its a boutique product.
Diesel used to be the stuff that condensed out right after kerosene in the frac column it was black thick and loaded with sulfur and benzene rings. Now it’s a custom made 15ppm max sulfur product that is hydrogen treated at the molecular level to remove sulfur and crack those benzene and other aromatics which are massive carcinogens to branched or linear isomers thus making them paraffins or waxes which also are removed and longer carcinogenic. Diesel today is clear , and thin it looks more like gasoline than gas oil of the last. One of the reasons diesel fuel injectors had to change their nozzle seats is diesel lacks its former lubricant properties sulfur was and is a fine lubricant.
So correct diesel is made on propose now and with great efforts to hit a very tight ppm max of S and also have enough centane index to fire off under compression. Taking the carcinogenic rings out raises its centane index but shifting to lighter CH2 chains lowers it still USA diesel is 45-55 centane and some of the best in the world its why we export it. That and the EU will pay $12 a DGE for it vs $6 here and it only costs $2 or less per gallon to ship it via bulk tanker across the ocean.