Assuming that $$ \lim_{n \to \infty} x^n = L $$ we must also have $$ xL = x \lim_{n \to \infty} x^n = \lim_{n \to \infty} x^{n+1} = L $$ so $xL = L$, so $x = 1$ or $L = 0$.
Now use our assumption that $x > 1$, so $L = 0$. But this is impossible, because $1 < x < x^2 < x^3 < \cdots$, implying that $|x^n - 0| > 1$ for all $n$.