The Chicago Manual says this on the subject of Dutch names:
Section 8.13 Dutch Names:
> In english usage, the particles van, van den, ter, and the like are lowercased when full names are given but usually capitalized when only the last name is used.
> Joannes van Keulen; Van Keulen
> Pieter van den Keere; Van den Keere
> Vincent van Gogh; Van Gogh
> Gerard ter Borch; Ter Borch