Kings and Queens of Denmark Alphabetically
Name– Details :
Abel –1 king
Christian –10 kings
Christoffer– 3 kings
Erik –7 kings
Frederik– 9 kings
Gorm –1 king
Hans 1 king
Harald –3 kings
Knud –5 kings
Magnus –1 king
Margrethe– 2 queens
Niels –1 king
Oluf –2 kings
Svend –3 kings
Valdemar– 4 kings

Danish monarchs chronologically (first to current. No mention of an Adolf–or Adolph–Ferdinand in either of these lists):
Name– Years– Also Known As
Gorm the Old– c.883-958
Harald I Bluetooth–941-985 (Harold)
Svend I Forkbeard– 991-1014 (Sweyn)
Harald II –1014-1018 (Harold)
Knud I the Great –1018-1035 (Canute)
Knud II the Hardy –1035-1042 (Hardicanute, Hardeknud, Canute)
Magnus the Good– 1042-1047
Svend II Estridsen –1047-1074 (Sweyn)
Harald III Hen– 1074-1080 (Harold)
Knud II the Holy– 1080-1086 (Canute)
Oluf I the Hungry –1086-1095 (Olaf)
Erik I the Evergood –1095-1103 (Eric)
Niels– 1104-1134 (Nicholas)
Erik II Emune– 1134-1137 (Eric)
Erik III the Lamb– 1137-1146 (Eric)
Svend III Grathe– 1146-1157 (Sweyn)
Knud III Magnussen– 1146-1157 (Canute)
Valdemar I the Great– 1154-1182 (Waldemar)
Knud (IV) VI –1182-1202 (Canute)
Valdemar II the Victorious– 1202-1241 (Waldemar)
Erik IV Ploughpenny– 1241-1250 (Eric)
Abel –1250-1252
Christoffer I –1252-1259 (Christopher)
Erik V Klipping– 1259-1286 (Eric)
Erik VI Menved– 1286-1319 (Eric)
Christoffer II –1320-1326/1330-1332 (Christopher)
Valdemar III –1326-1330 (Waldemar)
Valdemar IV Atterdag –1340-1375 (Waldemar)
Oluf II –1376-1387 (Olaf)
Margrethe I –1387-1412 (Margaret)
Erik VII of Pommerania– 1412-1439 (Eric)
Christoffer III of Bavaria –1440-1448 (Christopher)
Christian I –1448-1481
Hans –1481-1513 (John)
Christian II –1513-1523
Frederik I –1523-1533 (Frederick)
Christian III –1534-1559
Frederik II –1559-1588 (Frederick)
Christian IV– 1588-1648
Frederik III –1648-1670 (Frederick)
Christian V –1670-1699
Frederik IV –1699-1730 (Frederick)
Christian VI –1730-1746
Frederik V –1746-1766 (Frederick)
Christian VII –1766-1808
Frederik VI –1808-1839 (Frederick)
Christian VIII –1839-1848
Frederik VII –1848-1863 (Frederick)
Christian IX –1863-1906
Frederik VIII– 1906-1912 (Frederick)
Christian X– 1912-1947
Frederik IX –1947-1972 (Frederick)
Margrethe II –1972-present (Margaret)

Could this POSSIBLY be who you meant??
Albert Frederick, Duke of Prussia
(If so, see the article about him at ). This is the closest name and area I could find, after seeing no Danish king had the name you want.

Prussia was a historical region in Central Europe extending from the south-eastern coast of the Baltic Sea to the Masurian Lake District. It is now divided between Poland, Russia, and Lithuania. The former German state of Prussia derived its name from the region. The Vikings started to penetrate into Eastern Europe in the 7th and 8th centuries.
At the end of the Viking Age, the son of Danish king Harald Bluetooth and Canute the Great launched several expeditions against the Prussians, which resulted in far-spread destruction of many areas in Prussia including the destruction of Truso and Kaup, the largest trade centers of the Prussians. They failed to establish a firm foothold in Prussia, however.

I would suggest a trip to a good research library or local university. It’s a specialized area of research and while there may be bits and pieces on the internet, the real bulk of information will be shelved in Reference sections at larger libraries.