Process for producing n-pentanal comprising the following steps of: a) providing a feedstock mixture having the following composition which sums to 100 wt%: • n-butane: 70 wt% to 90 wt%; • n-butene: 10 wt% to 30 wt%; • 1-butene: 0 wt% to 3 wt%; • isobutene: 0 wt% to 3 wt%; • isobutane: 0 wt% to 3 wt%; • 1,3-butadiene: 0 wt% to 1 wt%; • other substances: 0 wt% to 1 wt%; b) mixing the feedstock mixture with a recyclate to obtain a feed; c) treating the feed with carbon monoxide and hydrogen in the presence of a first catalyst system to convert at least a portion of the n-butene present in the feed into aldehydes by hydroformylation to obtain a hydroformylation mixture; d) recovering a primary product fraction from the hydroformylation mixture, wherein the primary product fraction has the following composition which sums to 100 wt%: • n-pentanal: 90 wt% to 98.5 wt%; • 2-methylbutanal: 0 wt% to 5 wt%; • 3-methylbutanal: 0 wt% to 3 wt%; • other substances: 0 wt% to 2 wt%; e) recovering a subsidiary fraction from the hydroformylation mixture, wherein the subsidiary fraction has the following composition which sums to 100 wt%: • n-butane: 80 wt% to 92 wt%; • n-butene: 8 wt% to 20 wt%; • other substances: 0 wt% to 1 wt%; f) subjecting the subsidiary fraction to a dehydrogenation in the presence of a second catalyst system to obtain a dehydrogenation mixture having the following composition which sums to 100 wt%: • n-butene: 50 wt% to 60 wt%; • n-butane: 40 wt% to 50 wt%; • methane: 0 wt% to 4 wt%; • ethene: 0 wt% to 3 wt%; • propene: 0 wt% to 2 wt%; • 1,3-butadiene: 0 wt% to 3 wt%; • other substances: 0 wt% to 1 wt%; g) subjecting the dehydrogenation mixture to a selective hydrogenation in the presence of a third catalyst system to obtain a hydrogenation mixture having the following composition which sums to 100 wt%: • n-butene: 50 wt% to 60 wt%; • n-butane: 40 wt% to 50 wt%; • 1,3-butadiene: 0 ppm by weight to 500 ppm by weight; • other substances: 0 wt% to 5 wt%; h) direct use of the hydrogenation mixture as recyclate or purification of the hydrogenation mixture to obtain the recyclate, wherein the dehydrogenation is effected without addition of an oxidant or wherein the dehydrogenation is effected with addition of oxygen, wherein the added amount of oxygen based on the mass of the n-butane present in the subsidiary fraction is 1.4 wt% to 14 wt%. a) providing a feedstock mixture having the following composition which sums to 100 wt%: • n-butane: 70 wt% to 90 wt%; • n-butene: 10 wt% to 30 wt%; • 1-butene: 0 wt% to 3 wt%; • isobutene: 0 wt% to 3 wt%; • isobutane: 0 wt% to 3 wt%; • 1,3-butadiene: 0 wt% to 1 wt%; • other substances: 0 wt% to 1 wt%; b) mixing the feedstock mixture with a recyclate to obtain a feed; c) treating the feed with carbon monoxide and hydrogen in the presence of a first catalyst system to convert at least a portion of the n-butene present in the feed into aldehydes by hydroformylation to obtain a hydroformylation mixture; d) recovering a primary product fraction from the hydroformylation mixture, wherein the primary product fraction has the following composition which sums to 100 wt%: • n-pentanal: 90 wt% to 98.5 wt%; • 2-methylbutanal: 0 wt% to 5 wt%; • 3-methylbutanal: 0 wt% to 3 wt%; • other substances: 0 wt% to 2 wt%; e) recovering a subsidiary fraction from the hydroformylation mixture, wherein the subsidiary fraction has the following composition which sums to 100 wt%: • n-butane: 80 wt% to 92 wt%; • n-butene: 8 wt% to 20 wt%; • other substances: 0 wt% to 1 wt%; f) subjecting the subsidiary fraction to a dehydrogenation in the presence of a second catalyst system to obtain a dehydrogenation mixture having the following composition which sums to 100 wt%: • n-butene: 50 wt% to 60 wt%; • n-butane: 40 wt% to 50 wt%; • methane: 0 wt% to 4 wt%; • ethene: 0 wt% to 3 wt%; • propene: 0 wt% to 2 wt%; • 1,3-butadiene: 0 wt% to 3 wt%; • other substances: 0 wt% to 1 wt%; g) subjecting the dehydrogenation mixture to a selective hydrogenation in the presence of a third catalyst system to obtain a hydrogenation mixture having the following composition which sums to 100 wt%: • n-butene: 50 wt% to 60 wt%; • n-butane: 40 wt% to 50 wt%; • 1,3-butadiene: 0 ppm by weight to 500 ppm by weight; • other substances: 0 wt% to 5 wt%; h) direct use of the hydrogenation mixture as recyclate or purification of the hydrogenation mixture to obtain the recyclate, wherein the dehydrogenation is effected without addition of an oxidant or wherein the dehydrogenation is effected with addition of oxygen, wherein the added amount of oxygen based on the mass of the n-butane present in the subsidiary fraction is 1.4 wt% to 14 wt%.