A simple time crystal the idea of which "has been around for more than 100 years":

http://www.mdpi.com/1099-4300/19/1/34/pdf
"Catalysts have been used to assist in chemical reactions for about 200 years. They may speed up a reaction and lower energy requirements, but do not change the chemical equilibrium (completeness of a reaction). While they participate in reactions, they are not consumed.
The term "epicatalysis" is used to identify pairs of catalysts that oppose each other in assisting a chemical reaction, such that their chemical equilibrium points are different. The idea has been around for more than 100 years, with several supporting experiments.
If one puts two catalysts with opposing characteristics in contact with a bath of chemical reactants, per Figure 14, three things will occur:
* Catalyst 1 one will create Reactant Set A in favor of Reactant Set B, and Catalyst 2 will create Reactant Set B in favor of Reactant Set A.
* By diffusion, the bath will tend to equalize the reactants in the reverse direction, B diffusing toward Catalyst 1 and A toward Catalyst 2.
* One of the reactions (A = B or B = A) will generate more net heat (be exothermic) than the other, so the catalyst surface will warm, and the other will absorb more net heat (be endothermic).
The difference in net heat (and therefore temperature) may be used to drive a heat engine with no external cold side." [end of quotation]

Note that, in principle, the ETERNAL flows of reactants can also be harnessed to do work, at the expense of heat absorbed from the surroundings and in violation of the second law of thermodynamics.

Pentcho Valev