**Algorithm 1**

*XC*2*H*4 (%) = (*FC*2*H*4,*in* − *FC*2*H*4,*out*) *FC*2*H*4,*in YH*2 (%) = *FH*2 , 2 × *FC*2*H*4 in × 100 *YC* (%) = *mCdeposit mC*,*in* × 100 *mCdeposit* = *mcatalyst*,*t*<sup>0</sup> − *mcatalyst*,*<sup>t</sup> f* **For** DR: *mC*,*in* = ((2\* *FC*2*H*4,*in*\*time + *FCO*2,*in*\*time)) \* *MC* **For** CC: *mC*,*in* = ((2\* *FC*2*H*4,*in*\*time)) \* *MC* Carbon growth rate (gc·gcat<sup>−</sup>1·h−1) = *mCdeposit t* × *mcatalyst*,*t*<sup>0</sup> **where:**

*FC*2*H*4,*in* and *FC*2*H*4,*out* respectively denote the molar flow rates of C2H4 at the inlet and the outlet of the reactor, *FH*2 the molar flow rates of H2 at the outlet of the reactor

*mC*,*in* the mass of carbon fed.

*mCdeposit* the mass of solid carbon deposit on the catalyst *MC*the molar mass of C = 12.0107 g/mol
