Ammonolysis of phenol to aniline

Vapor-phase ammonolysis of phenol with excess ammonia to aniline plus water, per Figure 20.2 (p. 366) of Synthetic Nitrogen Products by Gary R. Maxwell (Kluwer, 2004). Unreacted ammonia and product water are let down to atmospheric and knocked out, then a column recovers the aniline. Phenol (bp 455 K) is very slightly MORE volatile than aniline (bp 457 K), so the aniline leaves as the bottoms and the residual water/ammonia plus the unreacted phenol go overhead. Honesty note: 2 K apart is a genuinely hard split — the aniline product comes out ~86 mol%, carrying ~14 mol% phenol, at ~91% recovery. A sharper cut is a much taller column, not a tuning change, and Peng-Robinson carries no aniline/phenol association to sharpen it.