Yes a fired heater with reaction taking place in furnace tubes - like a H2 plant seems appropriate A POX reactor (Hydrocarbon + O2 - but only enough for partial combustion is another possibility.

What chemical reaction? What is the assumed or actual enthalpy of the endothermic reaction? Moreover, what possible catalyst can withstand such high temperatures?

Miroslaw

Steam-methene reforming to produce h2. CH4 + H2O CO + 3 H2

Here is a catalyst for steam methane reforming:

https://www.topsoe.com/products/catalysts/r-67-7h

Zhen Yang Chua

Dear Zheng the best practical work is to design a molten salt bath which contains a mixture of sodium nitrite, sodium nitrate and potassium nitrate, then it should be heated via an electrical heater, and the internal temperature can be measured via a K-type thermocouple, the internal temperature can be maintained in the intended temperature via a temperature controller which is connected to the K-type thermocouple to measure the internal temperature all the time. You can immerse your reactor into the molten salt bath to provide the reaction heat.

By the way, 30 bar is not a very high pressure to build a high pressure reactor, but it is ideal to build a high pressure tubular reactor using high pressure tube and other kinds of high pressure joints.

I have the experience of working on both the supercritical water gasification and hydrothermal liquefaction processes, the highest temperature and pressure that I had performed was about 775 Celsius and 600 bars and it was performed via the aforementioned type of reactor and reaction media.

If you have any questions or need additional info don't hesitate to contact me.